Observe that the x coefficients are the same, whereas the y coefficients are opposite. This means that we can use elimation in two ways:
Method 1: SUM
If you sum the two equations, the opposite coefficients will cancel. The sum of the two equations is
[tex](x+y)+(x-y) = -4+2 \iff 2x=-2 \iff x=-1[/tex]
Substitute this value for x in the first equation (for example) and you have
[tex]-1+y=-4 \iff y=-3[/tex]
Method 1: SUBTRACT
If you subtract the two equations, the equal coefficients will cancel. The subtraction of the two equations is
[tex](x+y)-(x-y) = -4-2 \iff -2y=-6 \iff y=-3[/tex]
Substitute this value for y in the first equation (for example) and you have
[tex]x-3=-4 \iff x=-1[/tex]
