document.write( "Question 947446: A motorboat can go 16 miles downstream on a river in 20 minutes. It takes 30 minutes for this boat to go back upstream the same 16 miles. Find the speed of the boat in still water. \n" ); document.write( "

Algebra.Com's Answer #578094 by josmiceli(19441) $\"\"$ $\"About$

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$\"+20%2F60+=+1%2F3+\"$ hrs
\n" ); document.write( " $\"+30%2F60+=+1%2F2+\"$ hrs
\n" ); document.write( "Let $\"+s+\"$ = the speed of the boat in still water in mi/hr
\n" ); document.write( "Let $\"+c+\"$ = the speed of the current in mi/hr
\n" ); document.write( "----------------------------------
\n" ); document.write( "Going downstream:
\n" ); document.write( "(1) $\"+16+=+%28+s+%2B+c+%29%2A%281%2F3%29+\"$
\n" ); document.write( "Going upstream:
\n" ); document.write( "(2) $\"+16+=+%28+s+-+c+%29%2A%281%2F2%29+\"$
\n" ); document.write( "-------------------------
\n" ); document.write( "(1) $\"+s+%2B+c+=+48+\"$
\n" ); document.write( "(2) $\"+s+-+c+=+32+\"$
\n" ); document.write( "------------------
\n" ); document.write( "Add the equations
\n" ); document.write( " $\"+2s+=+80+\"$
\n" ); document.write( " $\"+s+=+40+\"$
\n" ); document.write( "and
\n" ); document.write( "(1) $\"+40+%2B+c+=+48+\"$
\n" ); document.write( "(1) $\"+c+=+8+\"$
\n" ); document.write( "----------------
\n" ); document.write( "The speed of the boat in still water is 40 mi/hr
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+s+-+c+=+32+\"$
\n" ); document.write( "(2) $\"+40+-+8+=+32+\"$
\n" ); document.write( "(2) $\"+32+=+32+\"$
\n" ); document.write( "OK
\n" ); document.write( " \n" ); document.write( "

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