You are going on a road trip over a distance of 3000 kilometers with three friends. the car consumes 6 liters of gas per 100 kilometers and gas costs $1.20 per liter.
if you want to split the cost of gas evenly between the four of you, how much should each of you chip in?

Let's make the rule of three: (To calculate the volume of gas spent by the distance traveled)

(volume)_____(Distance)
6 L ----------------- 100 Km
x L ----------------- 3000 Km

Directly proportional

multiply cross





Let's make the rule of three: (To calculate the amount of gas consumed by the volume in liters consumed).

(volume)_____(value)
1 L ----------------- $1.20
180 L ------------- $ y

Directly proportional

multiply cross



Now divide the value between the four friends:


Therefore:

Ithink if im not mistaking b is -3 but im not a 100% sude