I use simplified symbols to mark the corners directly. I hope there is no misunderstanding. ABCDP refers to its corresponding maximum angle.
D+A=B+C is obviously correct in eight characters.
At the same time, because PA and PC share A and C equally, just analogously, there are A/2+P=C/2+B and C/2+P = A/2+D. Add these two formulas directly, and 2p = B+D = 70 and P = 35.