Mr. Bailey mowed his yard in 90 minutes. His son Roy mows the yard in 75 minutes. How long will it take them if they work together (using 2 lawn mowers)?

Question

How to set up an equation? Thank you.

Answer 1

B does 1/90 yards/min
R does 1/75 yards/min

B+R together do (1/90 + 1/75)yards per minute

1/90 + 1/75 = .0244 yards/min
1/.0244 = 40.9 minutes/yard

Answer 2

Thank you so much!