We don't know what p represents, or it's a typo. Let's see what x and y are in terms of p:
-3x+6y=-3-p (1)
-6x+4y=-10⇒3x-2y=5 (2)
Add (1) and (2):
4y=2-p, y=¼(2-p),
Since 3x=5+2y=5+½(2-p)=5+1-p/2=6-p/2, x=2-p/6.
So if p=6, then x=2-6/6=2-1=1 and y=¼(2-6)=¼(-4)=-1.
This is the most likely answer (x=1, y=-1) so the question should have been written:
6-3x+6y=-3, -6x+4y=-10.