document.write( "Question 69992: Steve traveled 600 miles at a certain speed. Had he gone 20mph faster, the trip would have taken 1 hour less. Find the speed of his vehicle. Thank you in advance for the help! \n" ); document.write( "
Algebra.Com's Answer #49845 by Edwin McCravy(20060)\"\" \"About 
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document.write( "Steve traveled 600 miles at a certain speed.\r\n" );
document.write( "Had he gone 20mph faster, the trip would have \r\n" );
document.write( "taken 1 hour less. Find the speed of his vehicle. \r\n" );
document.write( "Thank you in advance for the help!\r\n" );
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document.write( "I'll do it a different way from Stanbon:\r\n" );
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document.write( "Let r be the actual rate and t be the actual time.\r\n" );
document.write( "Then the rate for the hypothetical trip would be r+20 and\r\n" );
document.write( "the time for the hypothetical trip would be t-1.\r\n" );
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document.write( "So put the information into a DRT chart:\r\n" );
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document.write( "                   DISTANCE   RATE    TIME\r\n" );
document.write( "Actual trip      |   600   |   r   |   t\r\n" );
document.write( "Hypothetical trip|   600   |  r+20 |  t-1\r\n" );
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document.write( "Now use DISTANCE = (RATE)(TIME)\r\n" );
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document.write( "     600 = rt\r\n" );
document.write( "     600 = (r+20)(t-1)\r\n" );
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document.write( "FOIL out the right side of the second equation:\r\n" );
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document.write( "     600 = rt - r + 20t - 20\r\n" );
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document.write( "Multiply the 1st equation by -1 and add it to\r\n" );
document.write( "the second equation\r\n" );
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document.write( "     600 =  rt - r + 20t - 20\r\n" );
document.write( "    -600 = -rt\r\n" );
document.write( "   ---------------------------\r\n" );
document.write( "       0 =      -r + 20t - 20\r\n" );
document.write( "       r = 20t - 20\r\n" );
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document.write( "Substitute in the first equation\r\n" );
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document.write( "     600 = rt\r\n" );
document.write( "     600 = (20t - 20)t\r\n" );
document.write( "     600 = 20tē - 20t\r\n" );
document.write( "       0 = 20tē - 20t - 600\r\n" );
document.write( "Divide every term through by 20\r\n" );
document.write( "       0 = tē - t - 30\r\n" );
document.write( "       0 = (t - 6)(t + 5)\r\n" );
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document.write( "t - 6 = 0     t + 5 = 0\r\n" );
document.write( "    t = 6 hrs     t = -5 hrs\r\n" );
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document.write( "We discard the negative answer.\r\n" );
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document.write( "To find r, substitute in\r\n" );
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document.write( "     600 = rt\r\n" );
document.write( "     600 = r(6)\r\n" );
document.write( "     600 = 6r\r\n" );
document.write( "     100 = r\r\n" );
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document.write( "So he traveled at 100 mi/hr.\r\n" );
document.write( "His vehicle must have been a\r\n" );
document.write( "small plane.\r\n" );
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document.write( "Edwin
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