Solve the Problem by Writing and Solving a Suitable System

Multiple Choice

Solve the problem by writing and solving a suitable system of equations.
-Carole's car averages 13.0 miles per gallon in city driving and 21.0 miles per gallon in highway driving. If she drove a total of 443.0 miles on 23 gallons of gas, how many of the gallons were used for city driving?

A) 23 gallons
B) 7 gallons
C) 18 gallons
D) 5 gallons