What is the largest number of regions formed by 6 planes in space?

This was part b of the problem, I already solved part a and I am confused on why it isn't the same answer as part a.

Part a's question:

By drawing 6 lines in the plane, what is the largest number of regions we can create?

I got an answer of 22 using a recursive formula: f(n) = f(n-1) + n.

Can anyone give me any hints on how to do part b?

all help is appreciated - Zekken4717

p.s this problem isn't due at any time so I have time to do it but quicker is better :)

p.s 22 is the right answer for part a.

Zekken Aug 8, 2021