I need help on my math homework

Question

Tommy mows lawns and cleans pools during the summer. He earns $20 per lawn and $9 per pool . He needs $1500 to buy a car from his friend . If tommy plans to mow 41 lawns this summer, how many pools must he clean to earn at least $1500

Answer 1

The amount of money that Tommy makes = 20*(# lawns mowed) + 9*(# pools cleaned)

Let's say

x = # lawns mowed

y = # pools cleaned

money made = 20x + 9y

He needs to make $1500.

1500 = 20*41 + 9y

1500 - 20*41 = 9y

(1500 - 20*41)/9 = y

y = 75.56

We must round up because Tommy cannot only partially clean a pool. He can buy a car with more than $1500, not less, so we round up. Tommy must clean 76 pools.