Question

A family has two cars. The first car has a fuel efficiency of 25 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 1525 miles, for a total gas consumption of 75 gallons. How many gallons were consumed by each of the two cars that week?

Answer 1

first car is x

second car is y

25x+30y=1550

x+y=55

Multiply the second equation by -25 for elimination method to cancel out x

-25x-25y=-1375

Add the two equations

5y=175

y=35

Plug this value into the second equation

x+35=55

x=20

Final answers:

First car=20 gallons

Second car=35 gallons