It is hard to read your images.
Solve for
Thank you so much!
I didn't know that P(C|D)+P(C|D') = P(C)!
If I expand it out eg. P(C|D)P(D) = P(CnD), it will be quite different from P(C|D')P(D') = P(CnD') so I dont think that's the proof..
Could you teach me how to prove P(C|D)+P(C|D') = P(C) using any method or even the venn diagram?