To do this, add the equations together like this,
3x + 4y = 2 plus
4x - 4y = 12
-x = 14
Multiply the negative sign to both sides because the x cannot be a negative.
x = -14
Now plug in -14 for a x value in one equation, like this to get the y value:
3(-14) + 4y = 2
-42 + 4y = 2
Add 42
4y = 44
y = 11
Your x and y values are:
x = -14
y = 11