SOLUTION: Guiseppe and norbert could go 78 miles downstream in the same time it took them to go 18 miles upstream. If the speed of their boat was 8 mph in still water, what was the speed of

Algebra ->  Test -> SOLUTION: Guiseppe and norbert could go 78 miles downstream in the same time it took them to go 18 miles upstream. If the speed of their boat was 8 mph in still water, what was the speed of       Log On


   

Question 330577: Guiseppe and norbert could go 78 miles downstream in the same time it took them to go 18 miles upstream. If the speed of their boat was 8 mph in still water, what was the speed of the current and what were their times ?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Rate*Time=Distance
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B=8
Let C be the current speed.
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Downstream:
%288%2BC%29T=78
1.8%2BC=78%2FT
Upstream:
%288-C%29T=18
2.8-C=18%2FT
Add the two equations,
8%2BC%2B8-C=%281%2FT%29%2878%2B18%29
16=%281%2FT%29%2896%29
T=6hr
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Then use either equation to solve for C.
8%2BC=78%2F6=13
C=5mph