5. Let A = {x, y}, B = {1,2}. Find the Cartesian products of A and B: A x B? (Hint: the result will be a set of pairs (a, b) where a ∈ A and b ∈ B).
6. Which if the following sets are equal?
a) {a, b, c, d}
b) {d, e, a, c)
c) {d, b, a, c}
d) {a, a, d, e, c, e}
7. What is the cardinality of each of the following sets?
a) { }
b) { { } }
c) {a, {a}, {a, {a}} }
8. How many different license plates can be made if each plate contains a sequence of three upper case English letters followed by three digits (and no sequences of letters are prohibited, even if they are obscene)?