document.write( "Question 628752: a motor boat can travel 9 miles/h up a river, and back downstream at 15 miles/h. find the rate of the motorboat in still water and the rate of the water current? \n" ); document.write( "

Algebra.Com's Answer #395817 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+b+\"$ = speed of boat in still water
\n" ); document.write( "Let $\"+c+\"$ = speed of water current
\n" ); document.write( "given:
\n" ); document.write( "(1) $\"+b+-+c+=+9+\"$
\n" ); document.write( "(2) $\"+b+%2B+c+=+15+\"$
\n" ); document.write( "---------------
\n" ); document.write( "Add the equations
\n" ); document.write( " $\"+2b+=+24+\"$
\n" ); document.write( " $\"+b+=+12+\"$
\n" ); document.write( "and
\n" ); document.write( "(2) $\"+12+%2B+c+=+15+\"$
\n" ); document.write( "(2) $\"+c+=+15+-+12+\"$
\n" ); document.write( "(2) $\"+c+=+3+\"$
\n" ); document.write( "The speed of the boat in still water is 12 mi/hr
\n" ); document.write( "The speed of the water current is 3 mi/hr \n" ); document.write( "

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