I got 7 if you are trying to look for the value of x than you multiply the bottom by two to have the y's equal. It should be
3x+2y=25
12x-2y=80
Since the twos mark each other out it would be
3x=25
12x=80
You add the top and bottom so it becomes one like this
15x=105
Divide 15 on both sides and it should give you 7.
X=7
