Use some thinking to answer the following question. You are filling up your car with gas. Your tank can hold 19 gallons. Your car started with x gallons in it. You paid $20 in gas. What was the cost of gas per gallon?
Options:
(A) 19/20
(B) x/20
(C) (19-x) /20
(D) x-19) /20
(E) 19+20/x
Amount of gas you added to your car: 19-x
Price per gallon: (19-x)/20 So the final answer is (C).