SOLUTION: Kari’s boat can move at a speed of 20 mph in still water. The boat travels 108 mi downstream in a river in the same time it takes to go 72 mi upstream. What is the speed of the riv

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Question 449546: Kari’s boat can move at a speed of 20 mph in still water. The boat travels 108 mi downstream in a river in the same time it takes to go 72 mi upstream. What is the speed of the river? Write your answer in the form # mph.

Answer by jorel1380(3719) About Me  (Show Source):
You can put this solution on YOUR website!
108/20+c=72/20-c
108(20-c)=72(20+c)
2160-108c=1440+72c
180c=720
c=4
The current is 4 mph..