document.write( "Question 211161: A farmer drives a tractor from one town to another a distance of 120 kilometers. He drives 10 kilometers per hour faster on the return trip, cutting 1 hour off the time. How fast does he drive each way? \n" ); document.write( "
Algebra.Com's Answer #159546 by stanbon(75887)\"\" \"About 
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A farmer drives a tractor from one town to another a distance of 120 kilometers. He drives 10 kilometers per hour faster on the return trip, cutting 1 hour off the time. How fast does he drive each way?
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\n" ); document.write( "1st trip DATA:
\n" ); document.write( "distance = 120 km ; rate = x km/hr ; time = d/r = 120/x hrs
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\n" ); document.write( "Return trip DATA:
\n" ); document.write( "distance = 120 km ; rate = x+10 km/hr ; rime = d/r = 120/(x+10) hrs
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\n" ); document.write( "Equation:
\n" ); document.write( "1st trip time - return trip time = 1 hr
\n" ); document.write( "120/x - 120/(x+10) = 1
\n" ); document.write( "120x + 1200 - 120x = x(x+10)
\n" ); document.write( "1200 = x^2+10x
\n" ); document.write( "x^2 + 10x - 1200 = 0
\n" ); document.write( "(x+40)(x-30) = 0
\n" ); document.write( "Positive solution:
\n" ); document.write( "x = 30 km/hr (rate on the 1st trip)
\n" ); document.write( "x+10 = 40 km/hr (rate on the return trip)
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "
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