SOLUTION: The speed of a current is 6mph. If a boat travels 60 miles downstream in the same time that it takes to travel 30 miles upstream,what is the speed of the boat in still water?

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Question 1114579: The speed of a current is 6mph. If a boat travels 60 miles downstream in the same time that it takes to travel 30 miles upstream,what is the speed of the boat in still water?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Speed of current c
Speed of boat if still water, r
t, time being same in both directions

system%28%28r%2Bc%29=60%2Ft%2C%28r-c%29=30%2Ft%29

GIVEN also c=6.
system%28r%2B6=60%2Ft%2Cr-6=30%2Ft%29
t%2F60=1%2F%28r%2B6%29
t=60%2F%28r%2B6%29
-
t%2F30=1%2F%28r-6%29
t=30%2F%28r-6%29
-
Solve this equation:
highlight_green%2860%2F%28r%2B6%29=30%2F%28r-6%29%29
-
2%2F%28r%2B6%29=1%2F%28r-6%29
r%2B6=2%28r-6%29
r%2B6=2r-12
highlight%2818=r%29