Solve the Problem $284 \mathrm{~km}$ , and the Trip Took $4 \mathrm{hr}$

Solve the problem.
-Janet drove $284 \mathrm{~km}$ , and the trip took $4 \mathrm{hr}$ . At what average rate was Janet traveling?

A) $71 \mathrm{~km} / \mathrm{hr}$
B) $\frac{1}{71} \mathrm{~km} / \mathrm{hr}$
C) $72 \mathrm{~km} / \mathrm{hr}$
D) $1136 \mathrm{~km} / \mathrm{hr}$