Solve the Problem $3 \mathrm{hr}$ With a 7 -Mph Current to Reach a Picnic Area

Multiple Choice

Solve the problem.
-A boat traveled for $3 \mathrm{hr}$ with a 7 -mph current to reach a picnic area. The return trip against the same current took $6 \mathrm{hr}$ . Find the speed of the boat in still water.

A) $49 \mathrm{mph}$
B) $21 \mathrm{mph}$
C) $28 \mathrm{mph}$
D) $84 \mathrm{mph}$