For this problem I drew a Venn diagram..

Sets A,B and C are subsets of U.

U= positive integers less than 16
A= prime numbers
B= factors of 36
C= multiples of 4

(A intersect B)' union C {?}

My answer:

The apostrophe stands for negation!
According to my Venn diagram, that means that I will negate 2 and 3 and include all if the other numbers, right? and then... Union with Set C, which contains 4,8 and12,right?

Therefore,

1,4,5,6,7,8,9,10,11,12,13,14,15 ( this is the negation of A intersect B, hence 2 and 3 are negated) union 4,8,12( this is set C)
I then looked for the matching numbers on either side of the union... And got...

{4,8,12}

I am bit confused on the notations..
So do I find. The matching numbers as mentioned previously or do I do that for only when it's an insersection?
Please post any helpful links that help me with these confusing notations!

A = {2,3,5,7,11,13}

B = {1,2,3,4,6,9,12}
c= {4,8,12,16}

Just noticed that in your listing of C you don't have the 16

Does that result in your difficulties?

A intersect B = {2,3)

(A intersect B)' = {1,4,5,6,7,8,9,10,11,12,13,14,15,16}
which in "union" with C
= {1,4,5,6,7,8,9,10,11,12,13,14,15,16}

All I see missing from your answer is that final 16