document.write( "Question 360239: For a certain 3-digit number, interchanging the first and last digits gives a 3-digit number 297 less than the original number. Doubling the first and last digits of the original number gives a 3-digit number and increases the sum of the digits to 15 what is the number? \n" ); document.write( "
Algebra.Com's Answer #257062 by ankor@dixie-net.com(22740) You can put this solution on YOUR website! Let 100x + 10y + z = a three digit number \n" ); document.write( ": \n" ); document.write( "Write an equation for each statement: \n" ); document.write( ": \n" ); document.write( "For a certain 3-digit number, interchanging the first and last digits gives \n" ); document.write( " a 3-digit number 297 less than the original number. \n" ); document.write( "100x + 10y + z = 100z + 10y + x + 297 \n" ); document.write( "100x - x + 10y - 10y = 100z - z + 297 \n" ); document.write( "99x = 99z + 297 \n" ); document.write( "Simplify, divide thru by 99 \n" ); document.write( "x = z + 3 \n" ); document.write( ": \n" ); document.write( "Doubling the first and last digits of the original number gives a 3-digit \n" ); document.write( " number and increases the sum of the digits to 15 \n" ); document.write( "2x + y + 2z = 15 \n" ); document.write( "Replace x with (z+3) \n" ); document.write( "2(z+3) + y + 2z = 15 \n" ); document.write( "2z + 6 + y + 2z = 15 \n" ); document.write( "4z + y = 15 - 6 \n" ); document.write( "4z + y = 9 \n" ); document.write( "y = -4z + 9 \n" ); document.write( "only two positive integer solutions here \n" ); document.write( "z=1, y=5, then x=4 \n" ); document.write( "451 is the number \n" ); document.write( "and \n" ); document.write( "z=2, y=1, then x=5 \n" ); document.write( "512 is the number, however, it says: \n" ); document.write( "\"Doubling the first and last digits gives a 3-digit number\", so it can,t be 512 \n" ); document.write( ": \n" ); document.write( " what is the number? 451 \n" ); document.write( ": \n" ); document.write( ": \n" ); document.write( "Check: \n" ); document.write( "451 - 154 = 297 \n" ); document.write( " \n" ); document.write( " |