SOLUTION: the speed of a boat in still water is 15 mph. the boat can travel 60 miles downstream in 2/3 the time it takes to travel 60 miles upstream. what is the rate of the current?

Question 372132: the speed of a boat in still water is 15 mph. the boat can travel 60 miles downstream in 2/3 the time it takes to travel 60 miles upstream. what is the rate of the current?
Found 2 solutions by nyc_function, Greenfinch:
Answer by nyc_function(2741) (Show Source): You can put this solution on YOUR website!
Here is your equation:

(2/3)x + 15 * 15x = 60

Can you finish?
Answer by Greenfinch(383) (Show Source): You can put this solution on YOUR website!
Downstream time is 60/(15 + c) Upstream time is 60/(15 - c)
Equation is therefore 3x60/(15 + c) = 2x 60/(15 - c)
So 180 (15 - c) = 120(15 + c)
2700 - 180c = 1800 + 120c
900 = 300c
c = 3
Check : Downstream at 18 mph takes 10/3 hours
Upstream at 12 mph takes 5 or 15/3 hours
Ratio is 3:2
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