document.write( "Question 531852: a car driven on a rough road on 25 kilometers per hour and on a concrete road on 70 kilometers per hour.it takes the car 5.5 hours to drive on 225 kilometers.how long does it take the car to drive on a concrete road? \n" ); document.write( "
Algebra.Com's Answer #350633 by ankor@dixie-net.com(22740)\"\" \"About 
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a car driven on a rough road on 25 kilometers per hour and on a concrete road on 70 kilometers per hour.it takes the car 5.5 hours to drive on 225 kilometers.
\n" ); document.write( "how long does it take the car to drive on a concrete road?
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\n" ); document.write( "Let t = time on a concrete road
\n" ); document.write( "Given the total time as 5.5 hrs, therefore
\n" ); document.write( "(5.5-t) = time on the rough road
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\n" ); document.write( "Write a distance equation, dist = speed * time
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\n" ); document.write( "Rough rd dist + smooth rd dist = 225 km
\n" ); document.write( "25(5.5-t) + 70t = 225
\n" ); document.write( "137.5 - 25t + 70t = 225
\n" ); document.write( "-25t + 70t = 225 - 137.5
\n" ); document.write( "45t = 87.5
\n" ); document.write( "t = \"87.5%2F45\"
\n" ); document.write( "t = 1.944 hrs or 1 + .944(60) = 1 hr 57 min on the smooth road
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\n" ); document.write( "Check this by finding the dist at each speed, (5.5-1.944=3.556)
\n" ); document.write( "25*3.556 = 88.89 km
\n" ); document.write( "70*1.944 = 136.10 km
\n" ); document.write( "----------------
\n" ); document.write( "total km: 224.99 km \n" ); document.write( "
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