Answer:
-1 gallons, or basically 0 gallons
Step-by-step explanation:
You can't have a negative gallon, so it will have to be called 0. An expression could be made, which is 9 - 2x. X is the number of hours, which is 5. 5 times 2 is 10, and subtracted from 9 is -1. However, for this to really make sense, it would have to be 4.5 (4 hours, 30 minutes) hours to completely empty Brianna's car of gas, not 5 hours.
