Sixty percent of the students at a certain school wear neither a ring nor a necklace. Twenty

Question:

Sixty percent of the students at a certain school wear neither a ring nor a necklace. Twenty percent wear a ring and 30 percent wear a necklace. If one of the students is chosen randomly, what is the probability that this student is wearing
(a) A ring or a necklace?
(b) A ring and a necklace?