Question 79505
Here is an answer to your system of linear equations, using the insertion method.
Eq. 1: {{{2x+y+4=0}}}
Eq. 2: {{{x-y+2=0}}}

Manipulating eq. 2 to only have x on the left hand side of the equal sign gives:
{{{x=y-2}}}

Then inserting this into eq. 1:
{{{2x+y+4=0}}}
{{{2(y-2)+y+4=0}}}
{{{2y-4+y+4=0}}}
{{{3y-4+4=0}}}
{{{3y=0}}}
{{{y=0}}}

We now know that y = 0, and we can now re-insert this into the manipulated eq. 2 to get x:
{{{x=y-2}}}
{{{x=0-2}}}
{{{x=-2}}}

y=0 and x=-2. If you control the answer by inserting the numbers into the equations you will see that it is correct.