document.write( "Question 316801: Marco’s speed riding up a hill is 40% of his speed riding down the hill. It takes him two hours longer to ride up the hill than it takes him to ride down the hill. How long, in hours, does it take him to ride down the hill? Express your answer as a common fraction. \n" ); document.write( "

Algebra.Com's Answer #226831 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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Marco’s speed riding up a hill is 40% of his speed riding down the hill.
\n" ); document.write( " It takes him two hours longer to ride up the hill than it takes him to ride down the hill.
\n" ); document.write( " How long, in hours, does it take him to ride down the hill?
\n" ); document.write( " Express your answer as a common fraction.
\n" ); document.write( ":
\n" ); document.write( "Let s = his speed down hill
\n" ); document.write( "then
\n" ); document.write( ".4s = his speed up hill
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\n" ); document.write( "Let one way distance = 10
\n" ); document.write( ":
\n" ); document.write( "Write a time equation: time = dist/speed
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\n" ); document.write( "Time up - time down = 2 hrs
\n" ); document.write( " $\"10%2F.4s\"$ - $\"10%2Fs\"$ = 2 hrs
\n" ); document.write( "multiply by .4s, results
\n" ); document.write( "10 - .4(10) = 2(.4s)
\n" ); document.write( ":
\n" ); document.write( "10 - 4 = .8s
\n" ); document.write( ":
\n" ); document.write( "6 = .8s
\n" ); document.write( "s = $\"6%2F.8\"$
\n" ); document.write( "s = 7.5 is the downhill speed
\n" ); document.write( "then
\n" ); document.write( ".4(7.5) = 3 is the uphill speed
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\n" ); document.write( "Find the time to ride down hill
\n" ); document.write( "10/7.5 = 1 $\"1%2F3\"$ hr
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\n" ); document.write( "Check solution by finding the time uphill
\n" ); document.write( "10/3 = 3 $\"1%2F3\"$ hr, a two hr difference \n" ); document.write( "

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