Noah can build an ark in 40 days. Together, Noah and his wife can build the ark in 24 days. How long would it take Noah's wife working alone?

Answer 1

How much would get done in 1 day?

1/40 + 1/w = 1/24

The common denominator is 120w. Once we apply it we only deal with the numerators.

3w + 120 = 5w

2w = 120

w = 60 days