Question

Espa

A family has two cars. During one particular week, the first car consumed 30 gallons of gas and the second consumed 20 gallons of gas. The two cars drove a
combined total of 1050 miles, and the sum of their fuel efficiencies was 45 miles per gallon. What were the fuel efficiencies of each of the cars that week?

Answer 1

• 30 mpg
• 15 mpg

Explanation:

Let x represent the fuel efficiency of one of the cars. Then 45-x is the fuel efficiency of the other. The total miles driven is then ...

miles = (gallons)×(miles/gallon)

20x +30(45-x) = 1050

-10x +1350 = 1050 . . . simplify

300 = 10x . . . . . . . . . . add 10x-1050

x = 30 . . . . . . . . . . . . . divide by 10

45-x = 45-30 = 15

The car using 20 gallons got 30 miles per gallon; the car using 30 gallons got 15 miles per gallon.