What is the probability that it is a letter in the word HEAD or a multiple of 3

A bin contains 10 cards labeled A-J and 10 cards labeled 1-10. The cards are shuffled and one card is chosen at random. What is the probability that it is a letter in the word HEAD or a multiple of 3?

favorable oucomes are H,E,A,D, 3,6,9 = 7
total outcomes = 20
Pr = 7/20 = 0.35 <-------