A family has two cars. During one particular week, the first car consumed 35 gallons of gas and the second consumed

25 gallons of gas. The two cars drove a combined total of

2150 miles, and the sum of their fuel efficiencies was

70 miles per gallon. What were the fuel efficiencies of each of the cars that week?

Call car one = o

Call car two = t

o = 35 gallons

t = 25 gallons

d1 = do

d2 = 2150 - do

effici_0 = e

effic_2 = 70 - e

35*e = do

25 * (70 - e) = 2150 - do Substitute do into this equation

25 * (70 - e) = 2150 - 35e Remove the brackets on the left

1750 - 25e = 2150 - 35e Add 35e to both sides

1750 - 25e + 35e = 2150 - 35e + 35e

1750 + 10e = 2150 Subtract 1750 from both sides.

1750 - 1750 + 10e = 2150 - 1750

10e = 400 Divide by 10

e = 40 Answer for Car 1

70 - e = effic2

70 - 40 = 30 Answer for Car 2