Alex doesn’t mind what socks he puts on in the morning. He has a pair of red socks and a pair of blue socks. Each morning he just takes out the first two socks he finds. So some mornings he wears a pair of red socks and some mornings he wears a pair of blue socks. But some mornings he wears a ‘silly pair’ consisting of one red and one blue sock.
If he gets a pair of green socks as well, how many different pairs of socks, silly and otherwise, can he wear?