Question

A family has two cars. The first car has a fuel efficiency of 20 miles per gallon of gas and the second has a fuel efficiency of 15 miles per gallon of gas. During one particular week, the two cars went a combined total of 950 miles, for a total gas consumption of 55 gallons. How many gallons were consumed by each of the two cars that week?

Answer 1

first car = 25 gallons ; second car = 30 gallons

Explanation:

x + y = 55

20x + 15y = 950

x = 55-y
20/5 x + 15/5 y = 950/5

4x + 3y = 190

4(55-y) + 3y = 190

220 - 4y + 3y = 190

-y = -220 + 190

-y = - 30

y = 30

x = 55 - 30

x = 25