document.write( "Question 61369: Solve the system by substitution. 3x – y = –7
\n" ); document.write( " x + y = –9 \n" ); document.write( "
Algebra.Com's Answer #42250 by stanbon(75887)\"\" \"About 
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Solve the system by substitution. 1st: 3x – y = –7
\n" ); document.write( " 2nd: x + y = –9
\n" ); document.write( "-----------
\n" ); document.write( "1st: y=3x+7
\n" ); document.write( "Substitute in 2nd to get:
\n" ); document.write( "x+3x+7=-9
\n" ); document.write( "4x=-16
\n" ); document.write( "x=-4
\n" ); document.write( "Substutute into 2nd to solve for y:
\n" ); document.write( "-4+y=-9
\n" ); document.write( "y=-5
\n" ); document.write( "Check in 1st as follows:
\n" ); document.write( "3(-4)-(-5)=-7
\n" ); document.write( "-12+5=-7
\n" ); document.write( "-7=-7
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "
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