Question

A new crew of painters takes two times as long as the old painters. Together they can paint in 6 hours. How many hours does it take the old painters to paint.

Answer 1

Let n be old painters time. Then the new painters are 2n. So:
1/n+1/2n=1/6
2+1=2n/6
2n=18
n=9
The old painters take 9 hours; the new ones take 18
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