Question 123840
1.{{{2x-y=-3}}}
2.{{{x+4y=9}}}
Let's use equation 2 to solve for x in terms of y, then substitute into 1.
2.{{{x+4y=9}}}
{{{x=9-4y}}}
1.{{{2x-y=-3}}}
{{{2(9-4y)-y=-3}}}
{{{18-8y-y=-3}}}
{{{18-9y=-3}}}
{{{-9y=-21}}}
{{{highlight(y=21/9=7/3)}}}
From 2,
{{{x=9-4y}}}
{{{x=9-4(7/3)}}}
{{{x=9-28/3}}}
{{{x=27/3-28/3}}}
{{{x=(27-28)/3}}}
{{{highlight(x=-1/3)}}}

{{{drawing( 300, 300, -3, 3, -3, 3,grid( 1 ),graph( 300, 300, -3, 3, -3, 3, 2x+3, (9-x)/4),circle( -1/3, 7/3, .1 ))}}}