Question 569591
It take you 2 min to wash a window, and takes your friend 3 minutes to wash a window. How long does it take the two of you to wash 25 windows if you work together?
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Let x = time (mins) for both to wash 25 windows
then
x(1/2 + 1/3) = 25
multiplying both sides by 6:
x(3 + 2) = 150
x(5) = 150
x = 150/5
x = 30 minutes