A boy spent 20% of his money on books and 20% of the remainder on food.If he had $2000 left, how much money did he have at first?

Observe that

5/12 = 1/4 + 1/6

so that

tan(5π/12) = tan(π/4 + π/6)

Then

tan(5π/12) = sin(π/4 + π/6) / cos(π/4 + π/6)

… = (sin(π/4) cos(π/6) + cos(π/4) sin(π/6)) / (cos(π/4) cos(π/6) - sin(π/4) sin(π/6))

… = (cos(π/6) + sin(π/6)) / (cos(π/6) - sin(π/6))

(since sin(π/4) = cos(π/4) = 1/√2)

… = (√3/2 + 1/2) / (√3/2 - 1/2)

… = (√3 + 1) / (√3 - 1)

… = (√3 + 1) / (√3 - 1) × (√3 + 1) / (√3 + 1)

… = (√3 + 1)² / ((√3)² - 1²)

… = ((√3)² + 2√3 + 1²) / (3 - 1)

… = (3 + 2√3 + 1) / 2

… = (4 + 2√3) / 2

… = 2 + √3 … … … (C)

If you insist on using the half-angle identity, recall that

sin²(x) = (1 - cos(2x))/2

cos²(x) = (1 + cos(2x))/2

==>   tan²(x) = (1 - cos(2x)) / (1 + cos(2x))

Let x = 5π/12. The angle x lies in the first quadrant, so we know tan(x) is positive.

==>   tan(x) = +√[(1 - cos(2x)) / (1 + cos(2x))]

We also know

cos(2x) = cos(5π/6) = -√3/2

which means

tan(x) = tan(5π/12) = √[(1 - (-√3/2)) / (1 + (-√3/2))]

… = √[(1 + √3/2) / (1 - √3/2)]

… = √[(2 + √3) / (2 - √3)]

… = √[(2 + √3) / (2 - √3) × (2 + √3) / (2 + √3)]

… = √[(2 + √3)² / (2² - (√3)²)]

… = √[(2 + √3)² / (4 - 3)]

… = √[(2 + √3)²]

… = 2 + √3

Answer:

2√10 km

Step-by-step explanation:

By Pythagoras theorem,

x^2 + 9^2 = 11^2

x^2 + 81 = 121

x^2 = 121 - 81

x^2 = 40

= 4 x 10

x^2 = 2^2 x 10

x = 2√10 km

environment is not natural uniform all from

Answer:

2nd option

Step-by-step explanation:

[tex]\frac{7\pi }{12}[/tex] is an angle in the second quadrant

Thus to find the reference angle, subtract from π , that is

r = π - θ

Answer:

£8520

43000-11000=32000

20/100×32000

£6400

48300-43000=5300

40/100×5300=2120

£8520

Answer: read below

Step-by-step explanation:

A circle graph is a graph showing proportions of thing that label the person by using different colours

Answer:

ok so on the left ill put minutes and on the right ill put dollars

150=7.50

220=11.00

250=12.50

275=13.75

so now lets break this down by dividing the smallest numbers by 2 a couple times

75=3.75(2)

25=1.25(3)

1=0.05(25)

so for every minute on the phone you pay 5 cents

Hope This Helps!!!

Answer:

for every minute on the phone you pay 5 cents, add brainly plz.

Step-by-step explanation:

Answer:

m(x)

Step-by-step explanation:

Answer:

B.

Step-by-step explanation:

Since the numbers in the root is all the same, lets say [tex]\sqrt{2}[/tex] is a variable.

7x[tex]\sqrt{2}[/tex] - 4[tex]\sqrt{2}[/tex] + x[tex]\sqrt{2}[/tex]

Group with like terms:

7x[tex]\sqrt{2}[/tex] + x[tex]\sqrt{2}[/tex] - 4[tex]\sqrt{2}[/tex]

Combine like terms:

8x[tex]\sqrt{2}[/tex] - 4[tex]\sqrt{2}[/tex]

There you have it! Since all the square roots are the same thing, we can treat them like variables.

the answer is B..................

Answer:

-60x

Step-by-step explanation:

Answer:

1.3

Step-by-step explanation:

The Rest Of Them Are Writen As Fractions

Answer:

[tex]\sqrt{10}[/tex]

NOTE: the other answer is WRONG...

irrational means can not be written as a fraction (with whole numbers)

4/3 = 1.33333333333

Step-by-step explanation:

Answer:

x - 2y + 8 = 0

Step-by-step explanation:

that is the procedure above

Answer:

the answer is rotation hope it helps ahhaha

Answer:

The total amount of celery and onion needed for the soup is 7/10 cup.

Step-by-step explanation:

2/4 + 1/5 = 7/10 cup.

hope it helped :)

mark me brainliest!

Answer:

Step-by-step explanation:

Let's call the number x. The statement "...2 times a number" if the number is x looks like this:

2x

"8 less than" that looks like this:

... - 8

Putting the whole thing together:

2x - 8

Answer:

C

Step-by-step explanation:

The vertex is the point where the 2 lines meet on the V shape

The vertex is at (3, 2 ) → C

Answer:

Option c is the answer I think so if the answer is correct plz mark me as brainliest

Answer:

(A)

Step-by-step explanation:

The bottom arrow goes to 5 1/2, and then because adding -3 is the same as subtracting 3, the top arrow correctly goes back 3, resulting in an answer of 2 1/2.

Hope it helps (●'◡'●)

Answer:

36π mm²

Step-by-step explanation:

Formula: πr²

r=radius

r=6

π6²=36π

Answer:

2.5 years

Step-by-step explanation:

The given amount invested, which is the principal, P = $16,800

The simple interest rate, R = 5% per annum

The intended total value of the investment, A = $18,900

The simple interest on the principal, I = A - P

∴ I = $18,900 - $16,800 = $2,100

The formula for the simple interest, I, is given as follows;

[tex]I = \dfrac{P \times R \times T}{100}[/tex]

Therefore, we have;

[tex]T = \dfrac{I \times 100}{P \times R}[/tex]

Plugging in the values, gives;

[tex]T = \dfrac{2,100 \times 100}{16,800 \times 5} =2.5[/tex]

The time it will take the investment to grow to $18,900 is T = 2.5 years

Answer:

the discount of the earbuds is $8.60

the final price is $34.40

Step-by-step explanation:

1. find 20% of 43:

43 x 0.2 = 8.60

2. subtract that from $43:

$43 - 8.60 = $34.40

the discount of the earbuds is $8.60

the final price is $34.40

Answer:

160=130+x

x=160-130

x=30

Answer:

p = 2/3

q = 1/2

Step-by-step explanation:

The given equation is ,

[tex]\sf\to px^2 + px + 3q = 1 + 2x [/tex]

We can write it as ,

[tex]\sf\to px^2 + px + 3q - 1 -2x=0 [/tex]

Rearrange the terms ,

[tex]\sf\to px^2 - 2x + px + (3q -1)=0 [/tex]

This can be written as ,

[tex]\sf\to px^2 + x ( p - 2) + (3q -1) =0[/tex]

Now wrt Standard form of a quadratic equation ,

[tex]\bf \implies ax^2+bx + c = 0 [/tex]

we have ,

We know that product of zeroes :-

[tex]\to \sf q \times \dfrac{1}{p} = \dfrac{3q-1}{p } \\\\\sf\to 3q - 1 = q \\\\\sf\to 2q = 1 \\\\\sf\to \boxed{ q =\dfrac{1}{2}}[/tex]

Sum of roots :-

[tex]\to \sf q + \dfrac{1}{p} = \dfrac{2-p}{p} \\\\\sf\to \dfrac{ qp + 1}{p}= \dfrac{2-p}{p} \\\\\sf\to qp + 1 = 2 - p \\\\\sf\to p/2 + p = 1 \\\\\sf\to 3p/2 = 1 \\\\\sf\to \boxed{ p =\dfrac{2}{3}}[/tex]

Answer:

x = 50.6

Step-by-step explanation:

Answer: x = 82°

Step-by-step explanation:

The angle on the other side of 108° can be calculated as 180° - 108° = 72°

All angles within a triangle add up to 180°, so the x-value can be found as:

x = 180° - 72° - 26° = 82°

Answer:

a). y = 7x - 46      b). y = -1/7x - 22/7

Step-by-step explanation:

a). y = 7x + b

-4 = 7(6) + b

-4 = 42 + b

-46 = b

y = 7x - 46

b). y = -1/7x + b

-4 = -1/7(6) + b

-4 = -6/7 + b

-22/7 = b

y = -1/7x - 22/7

Answer: y = 2x + 20; x is any real number greater than or equal to 0, and y is any real number greater than or equal to 20.

Step-by-step explanation:

Answer:

The second one is the answer.

Step-by-step explanation:

Objective: Linear Equation Problems.

Let model the equation given to us.

Vlad spent 20 minutes on his homework already and he complete x math problems every 2 minutes so we represent this as

[tex]y = 2x + 20[/tex]

X can be any real number greater than or equal zero because time isnt negative so anything below zero is wrong.

Y can be any real number but however since Vlad spent 20 mins on his homework already, he must spend over or equal to 20 minutes completing the total homework.

The second one is the answer

through my working i got to 41² is the hypotenuse.

21²+20²=c²

factor out the square

(21+20)²=c²

41²=c²

and 41² is 1681

Answer:

29 units

Step-by-step explanation:

i just took the quiz