Question

Find (A upside down U B) upside down U C, given

A = {s,e,t}
B = {m,E}
C = {f,r,e,e,}

Answer 1

Ok, that's A intersection B intersection C. You have to find out what they have in common with repeating any elements. The paranthesis means to do this first. A and B have an e in common. That e is also in C, so your answer is e.
(Side note: A U B means a union b. If you were asked to find this, you bring together everything in both sets without repeating. A U B would be s, e, m, t.)

Answer 2

So Would it be like this?

A,B, = e
C = e
AUB = s,e,m,t