A golf ball is selected at random from a golf bag. If the golf bag contains 5 type A balls, 4 type B

A golf ball is selected at random from a golf bag. If the golf bag contains 5 type A balls, 4 type B balls, and 9 type C balls, find the probability that the golf ball is not a type A ball

Not Type A means Type B or Type C.

Our total balls = 5 + 4 + 9 = 18

P(B or C) = P(B) + P(C)
P(B or C) = 4/18 + 9/18
P(B or C) = 13/18