document.write( "Question 718802: alvin paddled for 3 hours with a 6kmh current to reach a campsite. the return trip against the same current took 9 hours. find the speed of the boat in still water? \n" ); document.write( "

Algebra.Com's Answer #441066 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+s+\"$ = the speed in mi/hr of the boat in still water
\n" ); document.write( "Let $\"+d+\"$ = the one-way distance he paddles in miles
\n" ); document.write( "Going with the current:
\n" ); document.write( "(1) $\"+d+=+%28+s+%2B+6+%29%2A3+\"$
\n" ); document.write( "Going against the current:
\n" ); document.write( "(2) $\"+d+=+%28+s+-+6+%29%2A9+\"$
\n" ); document.write( "-------------------
\n" ); document.write( "By substitution:
\n" ); document.write( "(2) $\"+%28+s+%2B+6+%29%2A3+=+%28+s+-+6+%29%2A9+\"$
\n" ); document.write( "(2) $\"+3s+%2B+18+=+9s+-+54+\"$
\n" ); document.write( "(2) $\"+6s+=+18+%2B+54+\"$
\n" ); document.write( "(2) $\"+6s+=+72+\"$
\n" ); document.write( "(2) $\"+s+=+12+\"$
\n" ); document.write( "The speed of the boat in still water is 12 mi/hr
\n" ); document.write( "check answer:
\n" ); document.write( "(1) $\"+d+=+%28+12+%2B+6+%29%2A3+\"$
\n" ); document.write( "(1) $\"+d+=+18%2A3+\"$
\n" ); document.write( "(1) $\"+d+=+54+\"$
\n" ); document.write( "and
\n" ); document.write( "(2) $\"+d+=+%28+12+-+6+%29%2A9+\"$
\n" ); document.write( "(2) $\"+d+=+6%2A9+\"$
\n" ); document.write( "(2) $\"+d+=+54+\"$
\n" ); document.write( "OK\r
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