SOLUTION: Pratap Puri rowed 18 miles down the Delaware River in 2 hours, but the return trip took him 4 1/2 hours. Find the rate Pratap can row in still water, and find the rate of the curr

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Question 640951: Pratap Puri rowed 18 miles down the Delaware River in 2 hours, but the return trip took him 4 1/2 hours. Find the rate Pratap can row in still water, and find the rate of the current. let x = rate Pratap can row in still water and y = rate of the current.
Answer by lwsshak3(11628) About Me  (Show Source):
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Pratap Puri rowed 18 miles down the Delaware River in 2 hours, but the return trip took him 4 1/2 hours. Find the rate Pratap can row in still water, and find the rate of the current. let x = rate Pratap can row in still water and y = rate of the current.
**
x+y=speed downriver
x-y=speed return trip
travel time=distance/speed
..
18/(x+y)=2
18/(x-y)=4.5
..
2x+2y=18
4.5x-4.5y=18
..
multiply 1st equation by 2.25
4.5x+4.5y=40.5
4.5x-4.5y=18
add
9x=58.5
x=58.5/9=6.5
y=(18-2x)/2=2.5
rate Pratap can row in still water=6.5 mph
rate of the current=2.5 mph