Question

If A = {onion, pickles} and B = {onions, pickles, mustard, mayonnaise, lettuce}, what is AUB?

Answer 1

http://en.wikipedia.org/wiki/Union_(set_theory)

When you have the union of two sets, add them all into the same set.

Answer 2

{onions, pickles, mustard, mayonnaise, lettuce}

Answer 3

Yep.