bleach

From what I understand, you’re looking for dynamic delta hedging. I don’t have the question in front of me, but here’s my shot at it from the info in your question.
1. Find delta:
Cu-Cd / Su-Sd
20.86-2.68 / 78-53.95 = .7559 = delta
2. Find number of calls to short to delta hedge (objective is to get 1:1 value change):
1/.7559 = 1.3229 calls shorted for every share long.
The formula you’re presented seems like a method of figuring out how much the total position will cost you per call shorted.