document.write( "Question 430978: Please explain:
\n" ); document.write( "The excursion boat on the river takes 2.5 hours to make the trip to a point 12 miles upstream and to return. If the rate at which the boat travels in still water is 5 times the rate the river current, what is the rate of the current?
\n" ); document.write( "Whis equation can be used to solve for c?
\n" ); document.write( "(4c)(2.5) + (6c)(2.5) =24
\n" ); document.write( "(4c)(2.5) + (6c)(24) =2.5
\n" ); document.write( "[12/(4c)] +[12/(6c)] =2.5
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Algebra.Com's Answer #299243 by htmentor(1343) $\"\"$ $\"About$

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Let s = the speed in still water
\n" ); document.write( "Let c = the speed of the current
\n" ); document.write( "The speed on the upstream trip will be: s - c
\n" ); document.write( "The speed on the downstream trip will be: s + c
\n" ); document.write( "The total time required is the sum of the upstream and downstream times:
\n" ); document.write( "t = t_up + t_down = $\"d%2F%28s-c%29+%2B+d%2F%28s%2Bc%29\"$
\n" ); document.write( "Given: t = 2.5 hr, s = 5c, d = 12 mi
\n" ); document.write( "Therefore we have the following expression for the total time:
\n" ); document.write( " $\"2.5+=+12%2F%285c-c%29+%2B+12%2F%285c%2Bc%29\"$
\n" ); document.write( "This simplifies to:
\n" ); document.write( " $\"2.5+=+12%2F4c+%2B+12%2F6c\"$ \n" ); document.write( "

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