document.write( "Question 172884: A man leaves Paris driving at a constant speed. After a while he passes a kilometer stone that displays a 2 digit number. An hour later he passes another kilometer stone displaying the same 2 digit number but in reverse order. Another hour after that, he passes a 3rd kilomer stone marker with the same 2 digits(in any order seperated by a zero. What is the speed of the man's car? \n" ); document.write( "
Algebra.Com's Answer #127747 by ankor@dixie-net.com(22740)\"\" \"About 
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A man leaves Paris driving at a constant speed. After a while he passes a kilometer stone that displays a 2 digit number. An hour later he passes another kilometer stone displaying the same 2 digit number but in reverse order. Another hour after that, he passes a 3rd kilometer stone marker with the same 2 digits(in any order separated by a zero. What is the speed of the man's car?
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\n" ); document.write( "two digit x and y
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\n" ); document.write( "Let (10x + y) = 1st km marker
\n" ); document.write( "then: (10y + x) = 2nd km marker
\n" ); document.write( "and: (100x + y) = 3rd km marker
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\n" ); document.write( "2nd marker - 1st marker = 3rd marker - 2nd marker
\n" ); document.write( "(10y + x) - (10x + y) = (100x + y) - (10y + x)
\n" ); document.write( "10y + x - 10x - y = 100x + y - 10y - x
\n" ); document.write( "9y - 9x = 99x - 9y
\n" ); document.write( "Simplify, divide equation by 9
\n" ); document.write( "y - x = 11x - y
\n" ); document.write( "y + y = 11x + x
\n" ); document.write( "2y = 12x
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\n" ); document.write( "In order for y to equal a single digit, x has to = 1
\n" ); document.write( "2y = 12
\n" ); document.write( "y = 6
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\n" ); document.write( "1st marker = 16
\n" ); document.write( "2nd marker = 61
\n" ); document.write( "3rd marker = 106
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\n" ); document.write( "106 - 61 = 45 km in one hr therefore speed = 45 km/hr
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\n" ); document.write( "Check:
\n" ); document.write( "61 - 16 = 45 km \n" ); document.write( "
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