a) Let A = My son is younger than 18;
B = He (my son) loves golf
The logical statement is A * B
Where * is the logical "and" (intersection) operation. The statement can also be written as A ∩ B or just AB depending on which notation you're using.
DeMorgan's Theorem states:
NOT(A * B) = (NOT A) U (NOT B)
Where U is the "or" (union) operator. The symbol + is often used to denote the logical "or" operation as well, so A U B can be written as A + B
(NOT A) U (NOT B) = "My son is not younger than 18 or he does not love golf"
b) This one works the same as a). Try it and let me know what you get (in the comments).