Solve the Problem. -Fernando's Motorboat Can Travel 35 Mi/h in Still Water. If

Solve the problem.
-Fernando's motorboat can travel 35 mi/h in still water. If the boat can travel 7 miles downstream in the same time it takes to travel 3 miles upstream, what is the rate of the river's current?

A) 9 mi/h
B) 4 mi/h
C) 14 mi/h
D) 35 mi/h