You use the equation M=(x1+y2) divided by 2, and (y1+y2) divided by 2. So if you had the coordinates (3,4) and (4,5) the first part would use (3+4)/2 and the second part would be (4+5)/2. Solve for both separately. The answer for the first part would be: 7/2 as your X. So the answer for the second part would be: 9/2 as Y. Thus, the coordinates would be: (7/2, 9/2) as the midpoint