document.write( "Question 499424: solve the system of equation using substitution to eliminate one variable.
\n" ); document.write( "y=2x
\n" ); document.write( "3x+y=20
\n" ); document.write( "
\n" ); document.write( "I don't know how to work this out. \n" ); document.write( "
Algebra.Com's Answer #337666 by oberobic(2304)\"\" \"About 
You can put this solution on YOUR website!
y = 2x (given)
\n" ); document.write( "3x + y = 20 (given)
\n" ); document.write( ".
\n" ); document.write( "substitute y=2x in the second equation
\n" ); document.write( "so, you simply replace the 'y' with '2x'
\n" ); document.write( ".
\n" ); document.write( "3x + 2x = 20
\n" ); document.write( ".
\n" ); document.write( "5x = 20
\n" ); document.write( "x = 4
\n" ); document.write( ".
\n" ); document.write( "Now that you have x=4, you can find 'y'.
\n" ); document.write( ".
\n" ); document.write( "y = 2x
\n" ); document.write( "y = 2*4
\n" ); document.write( "y = 8
\n" ); document.write( ".
\n" ); document.write( "Now check your work using the other equation.
\n" ); document.write( "3x + y = 20
\n" ); document.write( "3x = 3*4 =12
\n" ); document.write( "y = 8
\n" ); document.write( "3x + y = 20
\n" ); document.write( "Correct.
\n" ); document.write( ".
\n" ); document.write( "You also can use graphs to see where the two lines intersect (which is (4,8)).
\n" ); document.write( "\"graph%28500%2C500%2C-10%2C10%2C-10%2C10%2C2%2Ax%2C-3%2Ax%2B20%29\"
\n" ); document.write( ".
\n" ); document.write( "Re-read the question to make sure you answer what was asked.\r
\n" ); document.write( "\n" ); document.write( "Answer:
\n" ); document.write( "x = 4
\n" ); document.write( "y = 8
\n" ); document.write( ".
\n" ); document.write( "Done.
\n" ); document.write( " \n" ); document.write( "
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