Amount of gas you added to your car: 19-x
Price per gallon: (19-x)/20
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:
[1] 19/20
[2] x/20
[3] (19-x) /20
[4] x-19) /20
[5] 19+20/x