Is $\ L = \{ \ w \in \{a, b, c\}^* \ | \ w = uv \ \ and \ \ \#_a(u) + \#_b(u) = \#_b(v) + \#_c(v) \ \} $ regular?
Your language is not regular, since
$$
L \cap a^*bc^* = \{ a^n b c^m : n \neq m \}.
$$
I'll let you figure out why.