Question

Betty can mow a lawn in 90 minutes. Melissa can mow the same lawn in 60 minutes. How long does it take for both Betty and Melissa to mow the lawn if they are working together? Express your answer as a reduced fraction.

____________ minutes

Answer 1

36 min

Explanation:

rate b = 1 / 90

rate m = 1/60

now add the rates together for 1 lawn

1 lawn / (1/60 + 1/90) = 36 min