 \vec{ MA }\;+\; \vec{ MB }\;=\;2 \vec{ MI }   

M = (18.479302000000004, -4.074389999999998)
A = (23.750062000000007, 3.158264000000003)
u = Vector(M, A)
B = (31.714766000000008, -4.132953999999998)
v = Vector(M, B)
a = Segment(A, B)
I = Midpoint(a)
w = Vector(M, I)