Inlet pipe #1 can fill a pool in 8 hours. Inlet pipes #1 and #2 together can fill the pool in 6 hours. How long will it take inlet pipe #2 to fill the pool by itself?

Lets say the total is 48 units of work

Pipe A can do 6 units of work per hour

A and B combined can do 8 units of work per hour

B can then do 2 units of work per hour

38/2 = 24

24 hours