I think I'm having a massive blonde moment...

How would I begin?

edit: also this question:

Here's my working so far:

I'm stuck here. I don't actually know what to do with multi-layered fractions, never been taught it.

I know the answer is

So clearly, I have to multiply by

How do I get there?

Also, this question:

part b,

Here's my working, I'm starting to think the question is wrong..?

What do I do from here?