I'm assuming you're trying to find out how much you'll spend annually on gas: first you would divide the total miles driven in a year (13,000) by your car's mpg (26) giving you a quotient of 500 (the amount of times you'll have to fill up your tank) from here you will need to multiply 500 times the cost of gas ($3.60) giving you a product of $1,800 spent on gas annually.
A (-12,-8), B(6,-3), C(3,3)
The product of 379 and 8 is 3,032.
It's between (any number less than 3,032) and (any number greater than 3,032).
I guess if this is an <em>estimation </em>exercise, you could say that it's between
(8 x 300) and (8 x 400), or 2,400 and 3,200.