
So here is the question..I am stuck on part c and onwards ( probably because next bits require some tricks used in (c) ). Any help how to do part c and maybe the rest :D Many thanks.

So here is the question..I am stuck on part c and onwards ( probably because next bits require some tricks used in (c) ). Any help how to do part c and maybe the rest :D Many thanks.
A hint: For (c), keep repeating the argument you used to use part (a). The other parts should all follow (almost) immediately from the result in (c).