At the same rate per square foot , Bert will take 80 minutes to mow the both lawns.
What is rate?
Rate is the ratio between two related quantities in different units.
Area of the rectangular lawn = lw
where
area of the lawn1 = 30 × 25 = 750 ft²
area of the lawn2 = 20 × 15 = 300 ft²
Therefore,
He mow the firts lawn 30 minutes longer than the second lawn. Therefore,
let
x = time to mow the second lawn
x + 30 = time to mow the first lawn
rate for the first lawn = 30 + x / 750
rate for the second lawn = x / 300
Hence,
30 + x / 750 = x / 300
cross multiply
9000 + 300x = 750x
9000 = 750x - 300x
9000 = 450x
x = 9000 / 450
x = 20
it will take him 30 + 20 + 20 = 80 minutes to mow the both lawns.
learn more on rate here: https://brainly.com/question/5219196
