Answer:
Hope this will help you
Step-by-step explanation:

36.89 total divided by the 8.6 gallons he bought = 4.2 so the price per gallon would be $4.20
X= -5/3 & x=5
I got this by using the quadratic formula.
The domain is all real numbers, reason being, you can put any number for x and get a valid coordinate.
Just plug in -1 for x and u should get ur answer