Question

Suppose you start with a full tank of gas (17 gallons) in your truck. After driving 3 hours, you now have 3 gallons left. If x is the number of hours you have been driving, then y is the number of gallons left in the tank. At what rate is the gas left in the tank changing

Answer 1

Explanation:

in 3 hours the truck used 17 - 3 = 14 gallons.

that means it used

14 gallons / 3 hours = 14/3 gallons / hour

and that means it is using

14/3 × x gallons in x hours

y = 17 - (14/3 × x)

the gas left in the tank is decreasing by 14/3 gallons per hour.