Question

Abe can mow the lawn in 15 minutes. Ben can mow the lawn in 20 minutes.Carl can mow the lawn in 30 minutes.They work together for 5 minutes.What part of the lawn was mowed?

a. 1/4
b. 2/3
c. 3/4
d. 4/5
e. all of it

please answer and explain

Answer 1

since 1/15 + 1/20 + 1/30 = 3/20, they can do the job together in 20/3 minutes.

5/(20/3) = 3/4