Solve the Problem $5 \mathrm{hr}$ To Fly $600 \mathrm{mi}$ Against a Head Wind

Multiple Choice

Solve the problem.
-An airplane took $5 \mathrm{hr}$ to fly $600 \mathrm{mi}$ against a head wind. The return trip with the same wind took 2 hr. Find the speed of the plane in still air.

A) $300 \mathrm{mph}$
B) $90 \mathrm{mph}$
C) $120 \mathrm{mph}$
D) $210 \mathrm{mph}$