On a weekened outing, Bernard rents a motorboat for 8 hours to travel down the river and back. The rental oper?

Question

On a weekened outing, Bernard rents a motorboat for 8 hours to travel down the river and back. The rental operator tells him to go for 3 hours downstream, leaving 5 hours to return upstream.
If the river current flows at a speed of 7 mph, how fast must Bernard travel in order to return in 8 hours?
? mph
How far downstream did Bernard go before he turned back?
? mi

ranjankar · Accepted Answer

Let Bernard's speed be x mph

DOWNSTREAM
------------------------

Speed = (x+7) mph

Distance traveled = 3(x+7)  miles

UPSTREAM
---------------------

Speed = ( x-7) mph 

Distance traveled = 5 (x-7)

3(x+7) = 5(x-7)

3x +21 = 5x -35

2x = 56

x = 28 mph ANSWER

3 ( 28+7) = 105 miles ANSWER

Mike G · Answer

3*(v+7) = 5(v-7)
3v+21 = 5v-35
2v = 56
v = 28 mph
s = 105 miles

On a weekened outing, Bernard rents a motorboat for 8 hours to travel down the river and back. The rental oper?

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