document.write( "Question 412621: Nancy can ride her bike uphill at eight kilometers per hour, and downhill at twelve kilometers per hour.She biked up the hill a certain distance and then biked back down the hill to her starting point.The entire trip took one hour.How far did she bike up the hill? \n" ); document.write( "

Algebra.Com's Answer #289782 by josmiceli(19441) $\"\"$ $\"About$

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she made 2 trips, one at 8 km/hr, the other at 12 km/hr
\n" ); document.write( "The total time was 1 hour
\n" ); document.write( "I'll say $\"t\"$ = time for uphill trip, $\"1-t\"$ = time for
\n" ); document.write( "downhill trip.
\n" ); document.write( "1st trip:
\n" ); document.write( " $\"d+=+8t\"$
\n" ); document.write( "2nd trip:
\n" ); document.write( " $\"d+=+12%2A%281+-+t%29\"$
\n" ); document.write( "This is 2 equations and 2 unknowns, so it's solvable
\n" ); document.write( "Set the $\"d\"$ 's equal to eachother (both trips are same distance)
\n" ); document.write( " $\"8t+=+12+-+12t\"$
\n" ); document.write( " $\"20t+=+12\"$
\n" ); document.write( " $\"t+=+3%2F5\"$ hr
\n" ); document.write( "Now solve for $\"d\"$
\n" ); document.write( " $\"d+=+8t\"$
\n" ); document.write( " $\"d+=+8%2A%283%2F5%29\"$
\n" ); document.write( " $\"d+=+24%2F5\"$ km
\n" ); document.write( " $\"d+=+4.8\"$ km
\n" ); document.write( "She biked 4.8 km up the hill
\n" ); document.write( "check answer:
\n" ); document.write( " $\"d+=+12%2A%281+-+t%29\"$
\n" ); document.write( " $\"d+=+12%2A%281+-+3%2F5%29\"$
\n" ); document.write( " $\"d+=+12%2A%282%2F5%29\"$
\n" ); document.write( " $\"d+=+24%2F5\"$
\n" ); document.write( "OK\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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