ANSWER
[tex]P(A\cap B)=0[/tex]
EXPLANATION
If the two events are disjoint, then they are mutually exclusive.
This means that their intersection is zero.
Therefore
[tex]n(A\cap B)=0[/tex]
This implies that,
[tex]P(A\cap B)= \frac{n(A\cap B)}{n(U)} [/tex]
[tex]P(A\cap B)= \frac{0}{n(U)} = 0[/tex]
The probability that the two events will occur together is 0, which means an impossibility.