The joint probability for P(M,P,W,B) is simply the product of the entries of the other tables. This is from Wikipedia:
X is a Bayesian network with respect to G if its joint probability density function (with respect to a product measure) can be written as a product of the individual density functions, conditional on their parent variables:
where pa(v) is the set of parents of v (i.e. those vertices pointing directly to v via a single edge).