Question

A family has two cars. The first car has a fuel efficiency of 15 miles per gallon of gas and the second has a fuel efficiency of 30 miles per gallon of gas. During

one particular week, the two cars went a combined total of 1050 miles, for a total gas consumption of 50 gallons. How many gallons were consumed by each of
the two cars that week?
First car: gallons
Second car: gallons

Answer 1

First car: 30 gallons

Second car: 20 gallons

Explanation:

Mark first car used gallons x, and second car used gallons y.

In total they consumed 50, so x + y = 50

In total they went 1050miles, so 15*x+30*y=1050

We get a system of equations. Solve the system.

Take first equation and solve x. x = 50 - y

Then insert x to second equation.

15*(50-y)+30*y=1050

750-15y+30y=1050

15y=1050 divide both sides by 15

y=20 gallons Found y.

Find x from x=50-y

x=50-20=30 gallons