SOLUTION: Mai is kayaking on a river that has a current of 2 miles per hour. If r represents her rate in calm water, then r+2 represents her rate with the current, and r-2 represents her rat

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Question 702780: Mai is kayaking on a river that has a current of 2 miles per hour. If r represents her rate in calm water, then r+2 represents her rate with the current, and r-2 represents her rate against the current. Mai kayaks 2 miles downstream and then back to her starting point. Use the formula for time, t=d/r, where d is the distance, to write a simplified expression for the total time it takes Mai to complete the trip.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +t+ = the total time for the trip
+t+=+d%2Fr+
given: +d+=+2+ mi
+t+=+2%2Fr+
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The rate of the current is +2+ mi/hr
Equation for going upstream:
+t%5B1%5D+=+2%2F%28+r+-+2+%29+
Equation for going downstream:
+t%5B2%5D+=+2%2F%28+r+%2B+2+%29+
+t+=+t%5B1%5D+%2B+t%5B2%5D+
+t+=+2%2F%28+r-2+%29+%2B+2%2F%28+r%2B2+%29+
+t+=+2%2A%28+1%2F%28+r-2%29+%2B+1%2F%28+r%2B2+%29%29+