document.write( "Question 262455: I am trying to help my niece with her homework and I need step-by-step instructions on how to use substitution to solve a system of equations.
\n" ); document.write( "Example:
\n" ); document.write( "2x + 3y = 5
\n" ); document.write( "4x - 9y = 9\r
\n" ); document.write( "\n" ); document.write( "Thanks for any help that you can share!! \n" ); document.write( "
Algebra.Com's Answer #193372 by stanbon(75887)\"\" \"About 
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I am trying to help my niece with her homework and I need step-by-step instructions on how to use substitution to solve a system of equations.
\n" ); document.write( "Example:
\n" ); document.write( "2x + 3y = 5
\n" ); document.write( "4x - 9y = 9
\n" ); document.write( "------
\n" ); document.write( "These are optional steps. There are many ways to
\n" ); document.write( "proceed.
\n" ); document.write( "----
\n" ); document.write( "1st: Solve the 1st equation for \"x\", as follows:
\n" ); document.write( "2x + 3y = 5
\n" ); document.write( "2x = -3y + 5
\n" ); document.write( "x = (-3y+5)/2
\n" ); document.write( "---------------------------
\n" ); document.write( "2nd: Substitute for \"x\" in the 2nd original equation and solve for \"y\":
\n" ); document.write( "4[(-3y+5)/2] - 9y = 9
\n" ); document.write( "2(-3y+5) - 9y = 9
\n" ); document.write( "-6y + 10 - 9y = 9
\n" ); document.write( "-15y = -1
\n" ); document.write( "y = 1/15
\n" ); document.write( "----------
\n" ); document.write( "Since x = (-3y+5)/2, x = (-3(1/15)+5)/2,
\n" ); document.write( "x = [(-1/5)+5/2 = (24/5)/2 = 12/5
\n" ); document.write( "------------------------
\n" ); document.write( "Final Answer: y = -1/3 when x = 12/5
\n" ); document.write( "=======================================
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
\n" ); document.write( " \n" ); document.write( "
\n" );