



 
Hi, The key to this problem is that
You have two equations, one from going upstream and the other for going downstream. The time is the same for each equation and the distances are 8 and 12 miles. Suppose that the rate of the current is $r$ miles per hour then the boat travels downstream at $r + 15$ miles per hour. What is the speed of the boat when travelling upstream? Solve for $r.$ Penny  


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