The current in a river is 10 mph. A boat can travel 50 mph in still water. How far up the river can the boat travel if the round trip is to take 5 hours?
Pick.
A) 120 B) 100 C) 96 D) 85 E) 150
Upstream Speed = 50-10= 
<gadget id="calculator">50-10</gadget>
<output>40</output>
40 mph   Downstream Speed= 50+10= 
<gadget id="calculator">50+10</gadget>
<output>60</output>
60 mph   D/40 + D/60= 5 hours   Solving for D we get D=120   120nswer: 120
<result>A</result>
The current in a river is 10 mph. A boat can travel 50 mph in still water. How far up the river can the boat travel if the round trip is to take 5 hours?