Part $1$: Deriving beam reactions a$)$ Separate your indeterminate beam into three determinate beam systems ; two primary $$ one with load P and one with load Q $-$ and one redundant. Take support C $($Cy$)$ to be the redundant $($force$).$ Note down the compatibility equation linking these three determinate beam systems. b$)$ Split these determinate beam systems either side of the internal pin and consider now only the beam system left of the internal pin $($section ABCD$).$ For the determinate system with load Q$,$ this will require you to split Q between the two parts.