document.write( "Question 134137: the sum of the last two digits of a three digit counting number is 7. the sum of the first two digits is 5. the middle digit is 4 times the first digit. what is the number? \n" ); document.write( "
Algebra.Com's Answer #98097 by solver91311(24713)\"\" \"About 
You can put this solution on YOUR website!
Three digit number, so the digits are h for hundreds, t for tens, and o for ones.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "The sum of the last two digits is 7: \"t+%2B+o+=+7\"
\n" ); document.write( "The sum of the first two digits is 5: \"h+%2B+t+=+5\"
\n" ); document.write( "The middle digit is 4 times the first digit: \"t=4h\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "We can substitute \"t=4h\" for \"t\" in \"h+%2B+t+=+5\" giving us \"h%2B4h=5\", and solve for h: \"5h=5\" => \"h=1\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Knowing that \"h=1\" we can use \"h%2Bt=5\" to determine that \"t=4\".\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Knowing that \"t=4\" we can use \"t%2Bo=7\" to determine that \"o=3\".\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Therefore the number is 143.\r
\n" ); document.write( "\n" ); document.write( "4 + 3 = 7
\n" ); document.write( "4 + 1 = 5, and
\n" ); document.write( "4 = 4(1)\r
\n" ); document.write( "\n" ); document.write( "Answer checks.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "
\n" );