Question

A family has two cars. The first car has a fuel efficiency of 40 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 1025 miles, for a total gas consumption of 35 gallons. How many gallons were consumed by each of the two cars that week?

Answer 1

I have problem here with just slight changes in the given values, this will help you to solve the problem.

Distance = Efficiency * Gallons

First car:
Distance = x
Efficiency = 20
Gallons = x/20

Second car:
Distance = 1300 - x
Efficiency = 15
Gallons = (1300 - x)/15

x/20 + (1300 - x)/15 = 75

3x/60 + 4(1300 - x)/60 = 75

3x/60 + (5200 - 4x)/60 = 75

(3x + 5200 - 4x)/60 = 75

(5200 - x)/60 = 75

5200 - x = 4500

x = 700

First car:
Gallons = x/20 = 700/20 = 35

Second car:
Gallons = (1300 - x)/15 = (1300 - 700)/15 = 600/15 = 40