Suppose you drive an average of 13,000 miles per​ year, and your car gets 25 miles per gallon. Suppose gasoline costs ​$3.20 a gallon.

Question

a. How much money do you spend each year on​ gasoline?

b. You plan to trade in your car for one that gets x more miles per gallon. Write an expression to represent the new yearly cost of gasoline.

c. Write an expression to represent your total savings on gasoline per year.

d. Suppose you can save ​$400 a year with the new car. How many miles per gallon does the new car​ get?

Answer 1

a. 13,000/25 = 520 gallons

520(3.2) = $1664

b. 3.2(13,000)/(25 + x)

c. 1264 = 3.2(13,000)/(25 + x)

1264(25 + x) = 3.2(13,000)

31,600 + 1264x = 41,600

1264x = 10,000

x = 8

25 + 8 = 33 mph