Jonah and his brother want to earn at least $400 this month, so they rented a lawn mower to mow lawns. They plan to charge $25 per lawn. The monthly rental fee for the lawn mower is $85. At this rate, what is the fewest number of lawns Jonah and his brother would have to cut to make their goal?

Answer 1

First, we must calculate the amount of money Jonah and his brother earn per lawn mowed by subtracting the rental fee from the amount charged: $25 - $85 = -$60
Per lawn, Jonah and his brother would actually lose $60.
To find the number of lawns they would have to mow, we divide the money they need to make by the amount they lose per lawn: $400 / -$60 = -6.666....
To have a positive answer, we round up to the nearest whole lawn, meaning they would have to mow 7 lawns. Answer: \boxed{7}.