Solve the problem below.

$*12-124.$ Before the uniform distributed load is applied on the beam, there is a small gap of $0\mathrm{.}2$ mm between the beam and the post at $B.$ Determine the support reactions at $A,B,$ and $C.$ The post at $B$ has a diameter of $40$ mm $,$ and the moment of inertia of the beam is $I=875({10}^6)m{m}^4.$ The post and the beam are made of material having a modulus of elasticity of $E=200$GPa.