3.8 hours but I am not sure
The time taken to take them all working together to wash the windows on three houses is D. 0.8 hours.
How to calculate the time?The time taken by both of them will be:
1/4 + 1/5 + 1/3= x
15/60 + 13/60 + 20/60
48/60 = x
Cross multiply
48x = 60
x = 48/60
x = 0.8 hours.
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