Question

A family has two cars. The first car has a fuel efficiency of 35 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 925 miles, for a total gas consumption of 35 gallons. How many gallons were consumed by each of the two cars that week?

Answer 1

The amount of gas consumed by first and second car were 20 gallons and 15 gallons respectively.

Explanation

Suppose,  $x$ gallons of gas were consumed by the first car.

As the total gas consumption in one week is 35 gallons, so the amount of gas consumed by second car will be:  $(35-x)$ gallons.

The first car has a fuel efficiency of 35 miles per gallon of gas and the second has a fuel efficiency of 15 miles per gallon of gas.

So, the distance traveled by the first car in $x$ gallons of gas $=35x$ miles and the distance traveled by the second car in $(35-x)$ gallons of gas $=15(35-x)$ miles.

Given that, the two cars went a combined total of 925 miles. So, the equation will be.....

$35x+15(35-x)=925\\ \\ 35x+525-15x=925\\ \\ 20x=925-525=400\\ \\ x=\frac{400}{20}=20$

So, the amount of gas consumed by the first car is 20 gallons and the amount of gas consumed by the second car is: (35 - 20) = 15 gallons.