algebra word problem

Question

It takes 20 minutes to fill a wading pool. The pool has developed a leak through which it will empty in 30 minutes. If the hole is not fixed, how long will it take to fill the wading pool?

Answer 1

In t minutes, t/20 of the pool is filled and t/30 of it is emptied.

 

t/20 - t/30 = 1        multiply both sides by LCM 60.

3t - 2t = 60

t = 60

 

The pool is filled in 60 minutes.