document.write( "Question 621903: How many solutions exist for the following system of equations?
\n" ); document.write( "-10x – 10y = 20
\n" ); document.write( " -10x + 6y = -108 \n" ); document.write( "
Algebra.Com's Answer #391029 by dragonwalker(73)\"\" \"About 
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equation 1: -10x – 10y = 20
\n" ); document.write( "equation 2: -10x + 6y = -108\r
\n" ); document.write( "\n" ); document.write( "rearrange equation 1: -10x = 20 + 10y
\n" ); document.write( "(unless you are switching all numbers to the opposite side you should change the sign of the ones switched)\r
\n" ); document.write( "\n" ); document.write( "Substitute into equation 2:\r
\n" ); document.write( "\n" ); document.write( "20 + 10y + 6y = -108\r
\n" ); document.write( "\n" ); document.write( "16y = -108 - 20
\n" ); document.write( "16y = -128\r
\n" ); document.write( "\n" ); document.write( "divide both sides by 16\r
\n" ); document.write( "\n" ); document.write( "16y/16 = -128/16
\n" ); document.write( "y = -8\r
\n" ); document.write( "\n" ); document.write( "No substitute back into equation 1:\r
\n" ); document.write( "\n" ); document.write( "-10x + 80 = 20
\n" ); document.write( "-10x = 20-80
\n" ); document.write( "-10x = -60\r
\n" ); document.write( "\n" ); document.write( "as both negative to find x we need to change both to positive
\n" ); document.write( "10x = 60\r
\n" ); document.write( "\n" ); document.write( "divide both sides by 10\r
\n" ); document.write( "\n" ); document.write( "10x/10 = 60/10
\n" ); document.write( "x = 6\r
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