SOLUTION: it takes bob the boy scout 10 hours to paddle upstreamin a distance of 15 miles.when he turns around he finds it only takes him 5 hours to paddle 22.5 miles with the current. Hoow

Question 271802: it takes bob the boy scout 10 hours to paddle upstreamin a distance of 15 miles.when he turns around he finds it only takes him 5 hours to paddle 22.5 miles with the current. Hoow fast is bob's boat going in still water and what is the speed of the current of the river?

Answer by dabanfield(803) (Show Source): You can put this solution on YOUR website!
it takes bob the boy scout 10 hours to paddle upstreamin a distance of 15 miles.when he turns around he finds it only takes him 5 hours to paddle 22.5 miles with the current. Hoow fast is bob's boat going in still water and what is the speed of the current of the river?
Let x be the speed in still water and c the current.
1.) 15 = (x-c)*10
2.) 22.5 = (x+c)*5
Expanding:
1.) 15 = 10x - 10c
2.) 22.5 = 5x + 5c
Multiply equation 2.) by 2:
2.) 45 = 10x + 10c
1.) 15 = 10x - 10c
Add these two equations:
60 = 20x
x = 3

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