Complicated Math

Question

One person can clean the house in 5 hours. If a second person helps clean the house, the job can be dangerous be in 2 hours. How long does it take the second person to clean the house?

Answer 1

1/5 + 1/x = 1/2

multiply each term by 10x to get

2x + 10 = 5x

3x = 10

x = 10/3 = 3 1/3 hours for the 2nd person