So let’s say you have (2,8) and (4,12)
Your x values are your first ones. So 2 and 4.
that formula is to find the midpoint so let 2 by x1 and 4 be x2. Add those together you get 6. Then divide by 2. Always by 2. You get 3. That’s the midpoint of those two points. Same thing for the y values.