\r\n" );
document.write( "Use the first equation to substitute 3a+b for 2c\r\n" );
document.write( "in the second equation:\r\n" );
document.write( "\r\n" );
document.write( "3b = 2c+a \r\n" );
document.write( "3b = 3a+b+a\r\n" );
document.write( "3b = 4a+b\r\n" );
document.write( "2b = 4a\r\n" );
document.write( " b = 2a\r\n" );
document.write( "Divide both sides by 2b, to get a/b on the right\r\n" );
document.write( "\r\n" );
document.write( "
\r\n" );
document.write( "
\r\n" );
document.write( "1:2 = a:b\r\n" );
document.write( "a:b = 1:2\r\n" );
document.write( "\r\n" );
document.write( "Substitute 2a for b in\r\n" );
document.write( "\r\n" );
document.write( "3a+b = 2c\r\n" );
document.write( "3a+2a = 2c\r\n" );
document.write( " 5a = 2c\r\n" );
document.write( "\r\n" );
document.write( "Divide both sides by 5c to get a/c on the left:\r\n" );
document.write( "\r\n" );
document.write( "
\r\n" );
document.write( "\r\n" );
document.write( "
\r\n" );
document.write( "\r\n" );
document.write( "a:c = 2:5\r\n" );
document.write( "\r\n" );
document.write( "So now we have:\r\n" );
document.write( "\r\n" );
document.write( "a:b = 1:2\r\n" );
document.write( "a:c = 2:5\r\n" );
document.write( "\r\n" );
document.write( "Since 'a' corresponds to 1 in the first equation and\r\n" );
document.write( "to 2 in the second equation, get them so that a corresponds\r\n" );
document.write( "to the same number in both by multiplying both parts of the \r\n" );
document.write( "first ratio 1:2 by 2, getting 2:4\r\n" );
document.write( "\r\n" );
document.write( "a:b = 2:4\r\n" );
document.write( "a:c = 2:5\r\n" );
document.write( "\r\n" );
document.write( "Now that a corresponds to the same number, 2, in both,\r\n" );
document.write( "we can conclude:\r\n" );
document.write( "\r\n" );
document.write( "a:b:c = 2:4:5\r\n" );
document.write( "\r\n" );
document.write( "Edwin
\n" );
document.write( "![\"\"](\"/images/stars/stars-13.gif\")
