Gallons of gas.

Question

A family has two cars. During one particular week, the first car consumed 25 gallons of gas and the second consumed 30 gallons of gas. The two cars drove a combined total of 950 miles, and the sum of their fuel efficiencies was 35 miles per gallon. What were the  fuel efdiencies of each of the cars that week?

Answer 1

x = fuel efficiency of the first car

y = fuel efficiency of the second car

 

x + y = 35

25x + 30y = 950

 

Solve for x and y.

y = 35 - x

25x + 30(35 - x) = 950

-5x = -100

 

x = 20 miles per gallon

 

y = 35 - x = 35 - 20 = 15 miles per gallon