Imagine that the price per gallon of gas with a $7 car wash is $3.19 and the price without the car wash is $3.39.

Question

Imagine that the price per gallon of gas with a $7 car wash is $3.19 and the price without the car wash is $3.39. When is it worth it to buy the car wash? When is it worth it if the car wash costs $2?

Answer 1

3.19G + 7 = 3.39G

.2G = 7

G = 35 gallons when it costs the same, with or without the car wash

buy more than 35 gallons and the car wash combo is cheaper

buy less than 35 gallons, go without the car wash

if the car wash costs $2

3.19 G + 2 = 3.39G

.2G = 2

G = 10 gallons makes the costs the same

buy more than 10 gallons then go with the car wash

buy less than 10 gallons go without the car wash