What is the midpoint in the shown line segment?

Explanation

M is the midpoint because it splits the line segment into two parts of equal length

In the figure, M is the midpoint of segment AB, because the measure of AM, which is written as m(AM) , is equal to the measure of MB which is written as m(MB).

m(AM) = 4 - 1 = 3   and 

m(MB) = 7 - 4 = 3

Since the measure of both segments is 3 units, we can detect that

m(AM) = m(MB)