1: 2x+y=3
5x-2y=12
2: Multiply the first equation by 2
(2) (2x+y=3) => 4x+2y=6
3: Add
4x+2y=6
+ 5x-2y=12
______________
9x=18 The y's cancel out
9x/9=18/9 The 9's cancel out
x=2
4: Plug (x=2) back into either equation but, I'm going to do the first one. It's easier.
2(2)+y=3
4+y=3
4-4+y=3-4 The 4's cancel out
y=-1
Answer: (12,-1)
If you plug (x) and (y) back in it will equal 3 for the first and 12 for the second.