Your uncle just bought a hybrid car and wants to take you and your siblings' camping. Before you leave for the trip your uncle fills up the car with 18 gallons of gas. After driving for 1 hour there are 16.5 gallons of gas left in the tank. Create a table, graph, and equation to determine the gallons of gas left in the car tank after driving to the campsite. Based on your information, is this scenario proportional or not? Why?