Maybe I'm missing something, but it seems to me that what you want is something like this:
A2 = Base price from location 1 (for example $100)
B2 = Membership price at location 1, 20% off = A2*0.8 ($80)
C2 = Membership price at location 2 = membership price at location 1 so = B2 ($80)
D2 = Non-member price at location 2 = C2 * 10/9 ($88.89)
(C2 isn't really needed, obviously, but I include it for clarity.)


If instead you want to start with the membership price, then this:
A2 = Membership price (e.g. $80)
B2 = Price at location 1 = A2 * 10/8 ($100)
C2 = Price at location 2 = A2 * 10/9 ($88.89)

Does that help at all?