document.write( "Question 1120004: Traffic reduces Jim’s usual speed by 10mph, which lengthened his 200mph trip by 1 hour. Find his average speed. \n" ); document.write( "
Algebra.Com's Answer #735648 by Alan3354(69443)\"\" \"About 
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Traffic reduces Jim’s usual speed by 10mph, which lengthened his 200mph trip by 1 hour. Find his average speed.
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\n" ); document.write( "t = usual travel time
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\n" ); document.write( "d = r*t = (r-10)*(t+1) = 200
\n" ); document.write( "r = 200/t
\n" ); document.write( "(200/t - 10)(t+1) = 200
\n" ); document.write( "200 + 200/t - 10t - 10 = 200
\n" ); document.write( "-10t - 10 + 200/t = 0
\n" ); document.write( "10t^2 + 10t - 200 = 0
\n" ); document.write( "t^2 + t - 20 = 0
\n" ); document.write( "(t+5)*(t-4) = 0
\n" ); document.write( "t = 4 hours
\n" ); document.write( "r = 200/4 = 50 mi/hr \n" ); document.write( "
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