document.write( "Question 893067: The sum of the digits of a two digit number is 9. If 9 is added to the number, then the digits are reversed.Find the number. \n" ); document.write( "
Algebra.Com's Answer #541043 by Edwin McCravy(20055)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "t = tens digit\r\n" );
document.write( "u = units (ones) digit\r\n" );
document.write( "10t+u = the number\r\n" );
document.write( "10u+t = the number with the digits reversed\r\n" );
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\n" ); document.write( "The sum of the digits of a two digit number is 9.
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document.write( "        t+u = 9\r\n" );
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\n" ); document.write( "If 9 is added to the number, then the digits are reversed.
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document.write( "  10t+u + 9 = 10u+t\r\n" );
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document.write( "So the system of equations is\r\n" );
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document.write( "       \"system%28t%2Bu+=+9%2C10t%2Bu%2B9+=+10u%2Bt%29\"\r\n" );
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document.write( "Solve the first equation for for t\r\n" );
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document.write( "        t+u = 9\r\n" );
document.write( "          t = 9-u\r\n" );
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document.write( "Substitute (9-u) for t in the second equation of the system:\r\n" );
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document.write( "    10t+u+9 = 10u+t\r\n" );
document.write( "10(9-u)+u+9 = 10u+(9-u)\r\n" );
document.write( " 90-10u+u+9 = 10u+9-u\r\n" );
document.write( "      99-9u = 9u+9\r\n" );
document.write( "         90 = 18u\r\n" );
document.write( "          5 = u\r\n" );
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document.write( "Substitut 5 for u in\r\n" );
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document.write( "          t = 9-u\r\n" );
document.write( "          t = 9-5\r\n" );
document.write( "          t = 4\r\n" );
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document.write( "The number is 45.\r\n" );
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document.write( "Checking: We add 9 to 45 and get 54, which is the number\r\n" );
document.write( "with the digits reversed.\r\n" );
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document.write( "Edwin
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