Of the 40 students in a gym class, 13 played volleyball, 12 ran track (4 of whom

Question:

Of the 40 students in a gym class, 13 played volleyball, 12 ran track (4 of whom did a push-up), and the remainder were absent.
(a) What proportion of the class ran track?
(b) What percentage played volleyball?
(c) What percentage of the runners did a push-up?
(d) What proportion of the class was absent?