document.write( "Question 420199: The sum of the digits of a two-digit number is 7. With the digits reversed the number is 5 times the tens digit of the original number. Find the original number. Thanks for the help. \n" ); document.write( "
Algebra.Com's Answer #293719 by ankor@dixie-net.com(22740)\"\" \"About 
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The sum of the digits of a two-digit number is 7.
\n" ); document.write( " With the digits reversed the number is 5 times the tens digit of the original number.
\n" ); document.write( " Find the original number.
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\n" ); document.write( "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( "\"The sum of the digits of a two-digit number is 7.\"
\n" ); document.write( "x + y = 7
\n" ); document.write( "x = (7-y); use this form for substitution
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\n" ); document.write( "\"With the digits reversed the number is 5 times the tens digit of the original\"
\n" ); document.write( "10y + x = 5x
\n" ); document.write( "10y = 5x - x
\n" ); document.write( "10y = 4x
\n" ); document.write( "Substitute (7-y) for x
\n" ); document.write( "10y = 4(7-y)
\n" ); document.write( "10y = 28 - 4y
\n" ); document.write( "10y + 4y = 28
\n" ); document.write( "14y = 28
\n" ); document.write( "y = 28/14
\n" ); document.write( "y = 2
\n" ); document.write( "then
\n" ); document.write( "7 - 2 = 5 is x
\n" ); document.write( ":
\n" ); document.write( "52 is the original number\r
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