The current in a river is 8 mph. A boat can travel 20 mph in still water. How far up the river can the boat travel if the round trip is to take 10 hours? Choose the correct answer:  A) 69 miles  B) 84 miles  C) 96 miles  D) 100 miles  E) 112 miles
Upstream Speed = 20-8= 
<gadget id="calculator">20-8</gadget>
<output>12</output>
12 mph   Downstream Speed= 20+8= 
<gadget id="calculator">20+8</gadget>
<output>28</output>
28 mph   D/12 + D/28= 10 hours   Solving for D we get D=84   Answer: 84 miles
<result>B</result>
The current in a river is 8 mph. A boat can travel 20 mph in still water. How far up the river can the boat travel if the round trip is to take 10 hours?