Question 1076229
Sailing upstream for 7 miles takes 1 hour, or an average rate of 7 miles per hour. Sailing downstream for 7 miles takes 11 minutes, or 11/60 of an hour, making an average rate of 38-2/11 mph. So, let b be the speed of the boat, and c be the speed of the current. Then:
b-c=7 or 77/11
b+c=420/11
Then:
2b=77+420/11
b=497/22=22.591 mph
c=343/22=15.591 mph
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