document.write( "Question 690416: A three-digit number is 198 less than the number when its digits are reversed. twice the sum of the digits is 5 more than 7 times the tens digit. the tens digit is 5 less than twice the hundreds digit. find the original number. \n" ); document.write( "
Algebra.Com's Answer #426433 by ankor@dixie-net.com(22740)\"\" \"About 
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let a = the 100's digit
\n" ); document.write( "let b = the 10's
\n" ); document.write( "let c = the units
\n" ); document.write( "then
\n" ); document.write( "100a+10b+c = the number
\n" ); document.write( "and
\n" ); document.write( "100c+10b+a = the number reversed
\n" ); document.write( ":
\n" ); document.write( "\"A three-digit number is 198 less than the number when its digits are reversed.\"
\n" ); document.write( "100a + 10b + c = 100c + 10b + a - 198
\n" ); document.write( "Combine like terms
\n" ); document.write( "100a - a + 10b - 10b + c - 100c = -198
\n" ); document.write( "99a - 99c = -198
\n" ); document.write( "Simplify, divide by 99
\n" ); document.write( "a - c = -2
\n" ); document.write( "a = c - 2
\n" ); document.write( ":
\n" ); document.write( "\"twice the sum of the digits is 5 more than 7 times the tens digit.\"
\n" ); document.write( "2(a+b+c) = 7b + 5
\n" ); document.write( "2a + 2b + 2c = 7b + 5
\n" ); document.write( "2a + 2b - 7b + 2c = 5
\n" ); document.write( "2a - 5b + 2c = 5
\n" ); document.write( ":
\n" ); document.write( "\" the tens digit is 5 less than twice the hundreds digit.\"
\n" ); document.write( "b = 2a - 5
\n" ); document.write( "replace a with (c-2)
\n" ); document.write( "b = 2(c-2) - 5
\n" ); document.write( "b = 2c - 4 - 5
\n" ); document.write( "b = 2c - 9
\n" ); document.write( ":
\n" ); document.write( "Back to the 2nd statement equation
\n" ); document.write( "2a - 5b + 2c = 5
\n" ); document.write( "replace a with c-2 and replace b with 2c-9
\n" ); document.write( "2(c-2) - 5(2c-9) + 2c = 5
\n" ); document.write( "2c - 4 - 10c + 45 + 2c = 5
\n" ); document.write( "2c - 10c + 2c + 41 = 5
\n" ); document.write( "-6c = 5 - 41
\n" ); document.write( "-6c = -36
\n" ); document.write( "c = 6
\n" ); document.write( "then
\n" ); document.write( "a = 6 - 2
\n" ); document.write( "a = 4
\n" ); document.write( "and
\n" ); document.write( "b = 2(6) - 9
\n" ); document.write( "b = 3
\n" ); document.write( ":
\n" ); document.write( "436 is the original number
\n" ); document.write( ":
\n" ); document.write( "See if that checks out; subtract from the reversed number.
\n" ); document.write( "634
\n" ); document.write( "436
\n" ); document.write( "----Subtract
\n" ); document.write( "198\r
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\n" ); document.write( "\n" ); document.write( "
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