document.write( "Question 897020: A man drove 156 miles at a constant rate. If he had driven 5 miles per hour faster he would have made the trip in 12 minutes less time. How fast did he drive? \n" ); document.write( "

Algebra.Com's Answer #543934 by stanbon(75887) $\"\"$ $\"About$

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A man drove 156 miles at a constant rate. If he had driven 5 miles per hour faster he would have made the trip in 12 minutes less time. How fast did he drive?
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\n" ); document.write( "Original DATA:
\n" ); document.write( "distance = 156 miles ; rate = x mph ; time = d/r = 156/x hrs
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\n" ); document.write( "New Conditions::
\n" ); document.write( "distance = 156 miles ; rate = (x+5) mph; time = d/r = 156/(x+5) hrs
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\n" ); document.write( "Equation::
\n" ); document.write( "Note: 12 minutes = 1/5 hr
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\n" ); document.write( "156/x - [156/(x+5)] = 1/5 hr
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\n" ); document.write( "156(x+5) - 156x = (x(x+5)/5
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\n" ); document.write( "156*5*5 = x^2 + 5x
\n" ); document.write( "x^2 + 5x - 3900 = 0
\n" ); document.write( "x = 60 mph
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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