document.write( "Question 584651: a boat went 15 miles downstream in 1 hour and then returned to its dock in 5/3 hours. if the current of the stream was constant, find the speed of the boat and speed of the current \n" ); document.write( "

Algebra.Com's Answer #372822 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+s+\"$ = the speed of the boat in still water
\n" ); document.write( "Let $\"+c+\"$ = the speed of the current
\n" ); document.write( " $\"+s+%2B+c+\"$ = the speed of the boat going with the current
\n" ); document.write( " $\"+s+-+c+\"$ = the speed of the boat going against the current
\n" ); document.write( "--------
\n" ); document.write( "(1) $\"+15+=+%28+s+%2B+c+%29%2A1+\"$
\n" ); document.write( "(2) $\"+15+=+%28+s+-+c+%29%2A%285%2F3%29+\"$
\n" ); document.write( "---------------------
\n" ); document.write( "(1) $\"+s+%2B+c+=+15+\"$
\n" ); document.write( "and
\n" ); document.write( "(2) $\"+s+-+c+=+%283%2F5%29%2A15+\"$
\n" ); document.write( "(2) $\"+s+-+c+=+9+\"$
\n" ); document.write( "Add the equations
\n" ); document.write( "(1) $\"+s+%2B+c+=+15+\"$
\n" ); document.write( "(2) $\"+s+-+c+=+9+\"$
\n" ); document.write( " $\"+2s+=+24+\"$
\n" ); document.write( " $\"+s+=+12+\"$
\n" ); document.write( "and, since
\n" ); document.write( "(1) $\"+s+%2B+c+=+15+\"$
\n" ); document.write( "(1) $\"+12+%2B+c+=+15+\"$
\n" ); document.write( "(1) $\"+c+=+3+\"$
\n" ); document.write( "The speed of the boat in still water is 12 mi/hr
\n" ); document.write( "The speed of the current is 3 mi/hr
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+15+=+%28+12+-+3+%29%2A%285%2F3%29+\"$
\n" ); document.write( "(2) $\"+15+=+9%2A%285%2F3%29+\"$
\n" ); document.write( "(2) $\"+15+=+15+\"$
\n" ); document.write( "OK \n" ); document.write( "

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