Question:

Let A = {a, b, c, d, e} and B = {a, b, c, d, e, f}. Find A - B and B - A?

How would I do A - B since both have similar letters besides the f in B? What I am seeing in A - B is everything in A but not in B. So would the answer be 0 for A - B? If so would I write it as {0}?