Thomas can do a job in 4 hours. Julia can do the same job in7 hours. How many hours will it take the two of them to do the job it they work together?

Answer 1

1/4 + 1/7 = 1/x

Solve for x, the number of hours.

1/x = 11/28
x = 28/11 = 2 6/11 hours
= 2 hours 33 minutes.