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

Multiple Choice

Solve the problem.
-A boat traveled for $3 \mathrm{hr}$ with a 3- $\mathrm{mph}$ 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) $36 \mathrm{mph}$
B) $21 \mathrm{mph}$
C) $12 \mathrm{mph}$
D) $9 \mathrm{mph}$