Question

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?

Answer 1

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

`(6)/(x) = (100)/(3000)`
multiply cross

`100*x = 6*3000`

`100x = 18000`

`x = (180\diagup\!\!\!\!0\diagup\!\!\!\!0)/(1\diagup\!\!\!\!0\diagup\!\!\!\!0)`

`\boxed{x = 180\:L}`

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

`(1)/(180) = (1.20)/(y)`
multiply cross

`1*y = 180*1.20`

`y = 216 \to \boxed{\$216}`

Now divide the value between the four friends:

`(216)/(4) = \boxed{\$54}`

Therefore:

`\underline{The\:gas\:cost\:evenly\:among\:the\:four\:will\:be\:\$\:54}`