x+2y=-10 -3x-2y=14

  x+2y= -10

-3x-2y=  14         add both equations

-2x = 4       divide both sides by -2

x = -2

And using the first equation to find y, we have

-2 + 2y = -10    add 2 to both sides

2y = -8     divide by 2 on both sides

y = -4