D= {m, n, p, q}
E= {3,6,8}
a) D x E = { (m, 3), (m, 6), (m, 8), (n, 3), (n,6), (n,8), (p, 3), (p, 6), (p, 8), (q, 3), (q, 6),
(q, 8) }
b) We need to know what a proper subset is.
Proper subset
A proper subset of a set A is a subset of A that is not equal to A. In other words, if B is a proper subset of A, then all elements of B are in A but A contains at least one element that is not in B.
From the above definition, we can say R is a proper subset of D x E because there are element in D x E that is NOT in R.