A family has two cars.

Question

A family has two cars. The first car has a fuel efficiency of 15

 miles per gallon of gas and the second has a fuel efficiency of 25

 miles per gallon of gas. During one particular week, the two cars went a combined total of 1175

 miles, for a total gas consumption of 55

 gallons. How many gallons were consumed by each of the two cars that week?

Answer 1

15X + 25(55-X) = 1175

-10X = 1175 -1375

10X =200

X = 20 gallons for the first car

55-20 = 35 gallons for the 2nd car