To find the midpoint, you are basically finding the average (or mean) between the two coordinates, J and N.
Start by finding the average between the x coordinates of J and N: 10 and -4. Add them together then divide the total by 2.
10 + (-4) = 6; 6/2 = 3
The average of the x coordinates is 3. Now find the average of the y coordinates. Start by adding -2 and 6 together then dividing the total by 2.
-2 + 6 = 4; 4/2 = 2
3 is the average of the x coordinates and 2 is the average of the y coordinates, so that means the midpoint of J and N must be (3, 2).