A sedan gets $21 \mathrm{mpg}$ in the city and $27 \mathrm{mpg}$ on the highway. A truck gets $15 \mathrm{mpg}$ in the city and $21 \mathrm{mpg}$ on the highway, Suppose that each vehicle travels $c$ miles in the city and $h$ miles on the highway. The sedan uses 12 gal of gasoline and the truck uses 16 gal. Solve the system of equations to determine the number of city miles driven and the number of highway miles driven.
Sedan: $\quad \frac{1}{21} c+\frac{1}{27} h=12$
Truck: $\quad \frac{1}{15} c+\frac{1}{21} h=16$