Good evening Sonia! Here are my workings for this question. As I do not usually deal with JC level questions (I last touched the entire syllabus years ago and now I am trying to recall them one by one as well), I am not so sure about my workings. My answer may be wrong. And in fact, I think that my solutions are too lengthy and there should be a shorter way to do this.

Let me know if you need more explanation.