document.write( "Question 174784: 3x-2.5y=7.125
\n" ); document.write( "2.5x-3y=7.3125\r
\n" ); document.write( "\n" ); document.write( "solve by addition method \n" ); document.write( "
Algebra.Com's Answer #129857 by actuary(112)\"\" \"About 
You can put this solution on YOUR website!
I'm not sure what you mean by the \"addition method\" but I would solve the system of linear equations by attenpting to eliminate one of the unknowns.\r
\n" ); document.write( "\n" ); document.write( "Multiply 3x-2.5y=7.125 by 2.5 (Equation #1)
\n" ); document.write( " and multiply 2.5x-3y=7.3125 by 3 (Equation #2)\r
\n" ); document.write( "\n" ); document.write( "We have 2.5*(3x-2.5y*)=2.5*(7.125)
\n" ); document.write( " 2.5*3*x - 2.5*2.5*y = 2.5*3*x-6.25*y = 17.8125 (#1)\r
\n" ); document.write( "\n" ); document.write( "and 3*2.5*x - 3*3*y = 3*7.3125* = 21.9375 (#2)\r
\n" ); document.write( "\n" ); document.write( "Subtract #2 from #1\r
\n" ); document.write( "\n" ); document.write( "-6.25*y + 9*y = 17.8125-21.9375\r
\n" ); document.write( "\n" ); document.write( "So 2.75*y = -4.125 or y = -4.125/2.75 = -1.5\r
\n" ); document.write( "\n" ); document.write( "Substitute -1.5 for y in equation #1
\n" ); document.write( "3*x - 2.5*(-1.5)=7.125
\n" ); document.write( "3*x + 3.75 = 7.125
\n" ); document.write( "3*x = 7.125 - 3.75 = 3.375
\n" ); document.write( "There x = 3.375/3 = 1.125\r
\n" ); document.write( "\n" ); document.write( "Check results\r
\n" ); document.write( "\n" ); document.write( "Using equation #1\r
\n" ); document.write( "\n" ); document.write( "3*(1.125)-2.5*(-1.5) = 3.375+3.75=7.125 (solution checks)
\n" ); document.write( " \n" ); document.write( "
\n" );