It's funny that you asked for my help because you assumed that I would know what I'm doing if I did help. But I don't. Odd.
PAB and PCB both = 90
APCB is a quadrilateral... so....
The other two angles will sum to 180
ABC + APC = 180
73 + APC = 180
APC = x = 180 - 73 = 107