What is [x + y = -4][x - y =2] solved for elimination ?

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

Substitute this value for x in the first equation (for example) and you have

Method 1: SUBTRACT

If you subtract the two equations, the equal coefficients will cancel. The subtraction of the two equations is

Substitute this value for y in the first equation (for example) and you have

10+4√2 is the answer. i dont have the time to explain.