Belton park resort Mar/june 19

sir in the bpp revision kit there is a question named belton park resort on page 51 , i did not even understand the topic where it came from . i am guessing it is from shutdown problems from your lectures but the approach is not the same as shutdown one . its incremental costs , inflow and outflows in the marking scheme ? what chapter is that covered in your online lectures ? i took it for relevent costing but it doesnt fit there too . this same question is in performance measurement section in kaplan revision kit but in bpp its in decision making ? what on earth is this question and which topic exactly is it from ? and how to do it ?