Edexcel A Level Philosophy

Hi
So I recently got my AS grades and I got an A in philosophy (85% UMS but getting one paper remarked hoping for a few more points) I was wondering what is the criteria for an A* because I just can't work it out
Is it 90% at AS and 90% at A2?
Or is it 90% at A2 and an average of 80% across AS and A2?
Can someone please help me understand? This is for edexcel philosophy and ethics
Thank you