You seem to be missing some information about E.
If E is the midpoint between D and F, then
E is (1,1) Take half of (4-2) = 1 and half of (5-3) = 1
E alphabetically does come between D and F.
Just average the x values and average the y values of the two points D and F
Or plot them graphically, carefully, maybe on some graph paper, and you'll
visually see the midpoint is at (1,1)