Since you have coordinates for the points M(-4,1), A(3,3), and N(2,-3) you can use the midpoint formula to find the coordinates of the midpoints.
Once you have those coordinates you can use the distance formula to find the distance between the points
I will leave you the midpoint formula to get started
((x1+x2/2, y1+y2/2)
Just plug in the data you have
You can look up the distance formula for the distance between two points
Give it a try.