Question

An Advertising firm has an old computer that can prepare a whole mailing in 6 hours. With the help of newer model the job is complete in 2 hours. How long would it take the newer model to do the job alone?

Answer 1

It would only take three hours.

Explanation:

1/6+1/x=1/2

x + 6=3x

6=2x

x=3hr