document.write( "Question 672743: If a two digit number is decreased by 45, the original number will be reversed. The number is 5 less than 8 times the sum of its digits. What is the number? (According to the answer in my book; they are showing 10x and x and no x and y or t and u). I need to know how they are doing it with just x and 10x. \n" ); document.write( "
Algebra.Com's Answer #418463 by ankor@dixie-net.com(22740)![]() ![]() You can put this solution on YOUR website! let x = the 10's digit \n" ); document.write( "let y = the units \n" ); document.write( "then \n" ); document.write( "10x+y = the original number \n" ); document.write( ": \n" ); document.write( "Write an equation for each statement; simplify: \n" ); document.write( ": \n" ); document.write( "\"If a two digit number is decreased by 45, the original number will be reversed.\" \n" ); document.write( "10x + y - 45 = 10y + x \n" ); document.write( "10x - x = 10y -y + 45 \n" ); document.write( "9x = 9y + 45 \n" ); document.write( "Simplify, divide thru by 9 \n" ); document.write( "x = y + 5 \n" ); document.write( ": \n" ); document.write( "\" The number is 5 less than 8 times the sum of its digits.\" \n" ); document.write( "10x + y = 8(x+y) - 5 \n" ); document.write( "10x + y = 8x + 8y - 5 \n" ); document.write( "10x - 8x = 8y - y - 5 \n" ); document.write( "2x = 7y - 5 \n" ); document.write( "Replace x with (y+5), from the 1st statment \n" ); document.write( "2(y+5) = 7y - 5 \n" ); document.write( "2y + 10 = 7y - 5 \n" ); document.write( "Get everything positive here \n" ); document.write( "10 + 5 = 7y - 2y \n" ); document.write( "15 = 5y \n" ); document.write( "y = 15/5 \n" ); document.write( "y = 3 \n" ); document.write( "then \n" ); document.write( "x = 3 + 5 \n" ); document.write( "x = 8 \n" ); document.write( ": \n" ); document.write( "83 = the original number \n" ); document.write( ": \n" ); document.write( ": \n" ); document.write( "See if that checks out in the 1st statement \n" ); document.write( "\"If a two digit number is decreased by 45, the original number will be reversed. \n" ); document.write( "83 - 45 = 38; confirms our solution\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |