Depends on if controlled serving or self serve.
Figure you will end up with at least 40 percent loss on the brisket but you should end up with 7lbs of meat 1/3 lb ber person = 21 servings. (unless they eat like my friends and then you will end up with around 15.)
You won't lose as much with the pork about 20/25 percent. So about 6lbs 1/4 lb per = 24.
I'm far from an expert but pretty much how I figure