If , Find the values of x and y.

If the set A has 3 elements and the set B={3,4,5}, then find the number of elements in (AB).

If G= {7,8} and H = {5,4,2}, find G H and H G.

State whether each of the following statements are true or false. If the statement is false, rewrite the given statement correctly.
a. If P = {m,n} and Q = {n,m}, then P Q = {(m,n),(n,m)}.
b. If A and B are non-empty sets, then A B is a non- empty set of ordered pairs (x,y) such that x A and y B.
c. If A = {1,2), B = {3,4}, then A (B ) = .

If A = {-1,1}, Find A A A.