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 35 miles per gallon of gas. During one particular week, the two cars went a combined total of 2400 miles, for a total gas consumption of 65 gallons. How many gallons were consumed by each of the two cars that week?

Firstcar:gallons

Secondcar:gallons

Answer 1

x + y = 65 where x = gallons used by first and y = gallons by second car

so fisrt car travelled 40 x miles and and second travelled 35y miles

40x + 35y = 2400......(1)

x + y = 65 Multiply this by 40:-

40x + 40y = 2600 ........(2)

subtract equation (1) from equation (2):-

5y = 200
y = 40

so x = 65 - 40 = 25


Answer is
First car :- 25 gallons
second car 40 gallons