# Probability of A given not B

So I have been given the following details:

$$p(a\mid b)=0.2\\ p(a\mid \lnot b)= 0.6$$

How would I use this to determine $$p(\lnot a\mid b)$$? Is there some kind of a formula/procedure I can use or is there incomplete information?

I don't think that $$p(\lnot a\mid b)= 1-p(a\mid b)$$, but I can't think of any other ways

Given b, either a or (not a) will happen for sure. Thus, $$P(a|b)+P(not\; a|b)=1$$ for sure.