SOLUTION: Adam and Natasha row their canoe 21 miles downstream in 3 hours. After a picnic, they row their canoe back upstream. After 4 hours of rowing, they only travel 20 miles. Assuming th

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Question 998700: Adam and Natasha row their canoe 21 miles downstream in 3 hours. After a picnic, they row their canoe back upstream. After 4 hours of rowing, they only travel 20 miles. Assuming that Adam and Natasha canoe at a constant rate, and that the river's current is constant, find the speed at which Adam and Natasha can row in still water.
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
               rate         time          distance
DOWN           r+c           3              21
UPST           r-c           4              20

system%28%28r%2Bc%29%2A3=21%2C%28r-c%29%2A4=20%29


system%28r%2Bc=7%2Cr-c=5%29
Two linear equation in two unknown variables.