Because X and Y are independent, the probability that both [tex]X=x[/tex] and [tex]Y=y[/tex] is equal to the product of the individual probabilities, i.e.
[tex]\mathbb P(X=x\,\land\,Y=y)=\mathbb P(X=x)\mathbb P(Y=y)[/tex]
Without knowing the individual probabilities, the question is impossible to answer. But in case you have more information than you've given, you should be all set.
