probability question

How do you find the probability of something "union" to something else. For ex. P(F U M). I know how to do intersect but not union. I have a completed table but don't know how to do "union". thanks,

An example of an OR may be, "what is the probability of being dealt a Heart OR a King from a deck of cards?".

\(\displaystyle P(K \;\ \cup \;\ H)=P(K)+P(H)-P(K\cap H)\)

See?. We have to subtract off the king of Hearts or else we'll over count.

\(\displaystyle \frac{4}{52}+\frac{13}{52}-\frac{1}{52}\)