document.write( "Question 1051834: Solve the problem of equations by substitution method
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Algebra.Com's Answer #667295 by ikleyn(52781) $\"\"$ $\"About$

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document.write( " x + 7y = 31   (1)\r\n" );
document.write( "2x + 3y =  7   (2)\r\n" );
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document.write( "From (1), express x = 31-7y, and then substitute it into (2). You will get\r\n" );
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document.write( "2*(31-7y) + 3y = 7.\r\n" );
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document.write( "Simplify:\r\n" );
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document.write( "62 - 14y + 3y = 7,\r\n" );
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document.write( "-14y + 3y = 7 - 62,\r\n" );
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document.write( "-11y = -55,\r\n" );
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document.write( "y =  = 5.\r\n" );
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document.write( "Then x = 31-7y = 31-7*5 = 31-35 = -4.\r\n" );
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document.write( "Answer.  x = -4, y = 5.\r\n" );
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\n" ); document.write( "\n" ); document.write( "On solving systems of linear equations in two unknowns see the lessons\r
\n" ); document.write( "\n" ); document.write( "    - Solution of a linear system of two equations in two unknowns by the Substitution method \r
\n" ); document.write( "\n" ); document.write( "    - Solution of a linear system of two equations in two unknowns by the Elimination method \r
\n" ); document.write( "\n" ); document.write( "    - Solution of a linear system of two equations in two unknowns using determinant \r
\n" ); document.write( "\n" ); document.write( "    - Geometric interpretation of a linear system of two equations in two unknowns \r
\n" ); document.write( "\n" ); document.write( "    - Solving word problems using linear systems of two equations in two unknowns \r
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