document.write( "Question 412453: The currents speed Is 3 mph. Sean kayaks 4mi upstream the same time it takes him 10 mi to go downstream. What's the speed of the kayak in still water???? \n" ); document.write( "

Algebra.Com's Answer #289719 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
$\"3\"$ mi/hr is the speed of current
\n" ); document.write( "Let $\"s\"$ = speed of kayak in still water
\n" ); document.write( "going downstream:
\n" ); document.write( "speed = $\"s+%2B+3\"$
\n" ); document.write( "going upstream:
\n" ); document.write( "speed = $\"s+-3\"$
\n" ); document.write( "------------------
\n" ); document.write( "given:
\n" ); document.write( "(1) $\"4+=+%28s+-+3%29%2At%0D%0Aand%0D%0A%282%29+%7B%7B%7B10+=+%28s+%2B+3%29%2At\"$
\n" ); document.write( "-----------------
\n" ); document.write( "This is 2 equation and 2 unknowns, so it's solvable
\n" ); document.write( "(1) $\"4+=+%28s+-+3%29%2At%0D%0A%0D%0A%281%29+%7B%7B%7B4+=+s%2At+-+3t\"$
\n" ); document.write( "(2) $\"10+=+s%2At+%2B+3t\"$
\n" ); document.write( "Subtract (1) from (2)
\n" ); document.write( "(2) $\"10+=+s%2At+%2B+3t\"$
\n" ); document.write( "(1) $\"-4+=+-s%2At+%2B+3t\"$
\n" ); document.write( " $\"6+=+6t\"$
\n" ); document.write( " $\"t+=+1\"$ hr
\n" ); document.write( "Now I plug this into (1) and solve for $\"s\"$
\n" ); document.write( "(1) $\"4+=+s%2A1+-+3%2A1\"$
\n" ); document.write( "(1) $\"4+=+s+-+3\"$
\n" ); document.write( "(1) $\"s+=+7\"$
\n" ); document.write( "The speed of the kayak in still water is 7 mi/hr
\n" ); document.write( "check answer:
\n" ); document.write( "(2) $\"10+=+%28s+%2B+3%29%2At\"$
\n" ); document.write( "(2) $\"10+=+%287+%2B+3%29%2A1\"$
\n" ); document.write( " $\"10+=+10\"$
\n" ); document.write( "OK\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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