The midpoint of the line having the endpoints 
and 
is 
basically average them
so given that the line has the endpoints of (-3,7) and (9,-2)
x₁=-3
y₁=7
x₂=9
y₂=-2
so the midpoint can be found by doing
the midpoint is
basically average them
so given that the line has the endpoints of (-3,7) and (9,-2)
x₁=-3
y₁=7
x₂=9
y₂=-2
so the midpoint can be found by doing
the midpoint is