Rational expressions and equations

Question

Two buckets are used to fill a large bathtub with water. Bucket A is larger, and by itself it can fill the bathtub in 20 minutes. Bucket B is smaller, and by itself it can fill the bathtub in 50 minutes. If the two buckets are used together, how much time (minutes) does it take to fill the bathtub?

Answer 1

Bucket A fills 1/20 of the bathtub in a minute

Bucket B fills 1/50 of the bathtub in a minute

 

Together they fill (1/20 + 1/50) = 7/100 of the bathtub in minute

 

Then it takes 100/7 ≈ 14.28 minutes to fill the bathtub using both buckets.