I need a little help with this question, I understand that to show a set is countable you have to show that it has a some sort of injection / surjection to N or R, i.e sets that are know to be countable, but i am still not quite sure how to show this has a function relation to either sets?

Any help appreciated.

thank you

p.s I need help with part b, I have done part a, although the diagram I drew does not help me understand the question any better.