BPP F7 P&R Kit Q76

The are a couple of elements with this question that I’m struggling with, even whilst looking at the solution.

Firstly in Part a) Where does the 88 for equity come from? Is it just a balancing figure or calculated in some other way?

Next in part b)
Return on Shareholders’ equity = Profit after tax and Pref divident / Equity shareholders funds
So for HCA we use 12/62 = 19.4% as per solution, but using CCA they give 4/88 = 4.5%.
Even once you’ve worked out the 88 in part a I don’t see where this 4 comes from, should it not be 7/88?

Thanks in advance for the help!