Question 54537
Rate: 1/4
Time = t
Rate * Time = Work
t/4 = Work
Rate: 1/5
Time = t
Work = t/5
t/4 + t/5 = 1
20t/4 + 20t/5 = 20
5t + 4t + 20
9t = 20
t = 20/9
or 2 hours 13 minutes