document.write( "Question 418987: A ferry leaves a harbor and travels to a resort island at an average speed of 20 mph. On the return trip, the ferry travels at an average speed of 10 mph because of fog. The total time for the trip is 3 h. How far is the island from the harbor? \n" ); document.write( "

Algebra.Com's Answer #293088 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"d\"$ = distance to island from harbor
\n" ); document.write( "given:
\n" ); document.write( "Trip to island:
\n" ); document.write( " $\"+d+=+20%2At1\"$
\n" ); document.write( "Trip back:
\n" ); document.write( " $\"d+=+10%2At2\"$
\n" ); document.write( "-----------
\n" ); document.write( " $\"t1+%2B+t2+=+3\"$
\n" ); document.write( "This is 3 equations and 3 unknowns,
\n" ); document.write( "so it's solvable
\n" ); document.write( "----------
\n" ); document.write( " $\"t1+=+d%2F20\"$
\n" ); document.write( " $\"t2+=+d%2F10\"$
\n" ); document.write( "and
\n" ); document.write( " $\"d%2F20+%2B+d%2F10+=+3\"$
\n" ); document.write( " $\"d+%2B+2d+=+60\"$
\n" ); document.write( " $\"3d+=+60\"$
\n" ); document.write( " $\"d+=+20\"$
\n" ); document.write( "The island is 20 miles from the harbor
\n" ); document.write( "check:
\n" ); document.write( " $\"20+=+20%2At1\"$
\n" ); document.write( " $\"t1+=+1\"$
\n" ); document.write( "and
\n" ); document.write( " $\"20+=+10%2At2\"$
\n" ); document.write( " $\"t2+=+2\"$
\n" ); document.write( " $\"1+%2B+2+=+3\"$
\n" ); document.write( "OK \n" ); document.write( "

\n" );