document.write( "Question 621016: A tugboat goes 160 miles an hour upstream in 20 hrs. The return trip downstream takes 10 hrs. Find the speed of the tugboat without a current and the speed of the current. \n" ); document.write( "

Algebra.Com's Answer #390512 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+s+\"$ = the speed of the tugboat without a current
\n" ); document.write( "Let $\"+c+\"$ = the speed of the current
\n" ); document.write( "Going upstream:
\n" ); document.write( "(1) $\"+160+=+%28+s+-+c+%29%2A20+\"$
\n" ); document.write( "-------------
\n" ); document.write( "Going downstream:
\n" ); document.write( "(2) $\"+160+=+%28+s+%2B+c+%29%2A10+\"$
\n" ); document.write( "--------------------
\n" ); document.write( "(1) $\"+s+-+c+=+8+\"$
\n" ); document.write( "and
\n" ); document.write( "(2) $\"+s+%2B+c+=+16+\"$
\n" ); document.write( "---------------
\n" ); document.write( "Add (1) and (2)
\n" ); document.write( "(1) $\"+s+-+c+=+8+\"$
\n" ); document.write( "(2) $\"+s+%2B+c+=+16+\"$
\n" ); document.write( " $\"+2s+=+24+\"$
\n" ); document.write( " $\"+s+=+12+\"$
\n" ); document.write( "and, since
\n" ); document.write( "(1) $\"+s+-+c+=+8+\"$
\n" ); document.write( "(1) $\"+12+-+c+=+8+\"$
\n" ); document.write( "(1) $\"+-c+=-4+\"$
\n" ); document.write( "(1) $\"+c+=+4+\"$
\n" ); document.write( "The speed of the tugboat without a current is 12 mi/hr
\n" ); document.write( "The speed of the current is 4 mi/hr
\n" ); document.write( "check:
\n" ); document.write( "(1) $\"+160+=+%28+s+-+c+%29%2A20+\"$
\n" ); document.write( "(1) $\"+160+=+%28+12+-+4+%29%2A20+\"$
\n" ); document.write( "(1) $\"+160+=+8%2A20+\"$
\n" ); document.write( "(1) $\"+160+=+160+\"$
\n" ); document.write( "OK \n" ); document.write( "

\n" );