document.write( "Question 921283: A ferry moves up and down a river between Town A and B. It takes the ferry two hours to reach Town A and only an hour and thirty minutes to return to Town B. If the river current is 5 mph how far apart are the two cities? \n" ); document.write( "

Algebra.Com's Answer #558919 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+s+\"$ = the speed of the ferry in still water
\n" ); document.write( "Let $\"+d+\"$ = the distance between the towns
\n" ); document.write( "(1) $\"+s+-+5+=+d%2F2+\"$ = speed going from B to A
\n" ); document.write( "(2) $\"+s+%2B+5+=+d%2F1.5+\"$ = speed going from A to B
\n" ); document.write( "---------------------
\n" ); document.write( "(1) $\"+2s+-+10+=+d+\"$
\n" ); document.write( "and
\n" ); document.write( "(2) $\"+1.5s+%2B+7.5+=+d+\"$
\n" ); document.write( "----------------------
\n" ); document.write( "By substitution:
\n" ); document.write( " $\"+1.5s+%2B+7.5+=+2s+-+10+\"$
\n" ); document.write( " $\"+.5s+=+17.5+\"$
\n" ); document.write( " $\"+s+=+35+\"$
\n" ); document.write( "and
\n" ); document.write( "(1) $\"+2s+-+10+=+d+\"$
\n" ); document.write( "(1) $\"+2%2A35+-+10+=+d+\"$
\n" ); document.write( "(1) $\"+d+=+70+-+10+\"$
\n" ); document.write( "(1) $\"+d+=+60+\"$
\n" ); document.write( "The towns are 60 mi apart
\n" ); document.write( "----------
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+1.5s+%2B+7.5+=+d+\"$
\n" ); document.write( "(2) $\"+1.5%2A35+%2B+7.5+=+60+\"$
\n" ); document.write( "(2) $\"+52.5+%2B+7.5+=+60+\"$
\n" ); document.write( "(2) $\"+60+=+60+\"$
\n" ); document.write( "OK\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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