I believe the answer is the last option choice.
Not a 5 dollar just means a 10 dollar
probblity=desired outcomes/total possible outcomes
desired=number of 10 dollar notes or 30
total possible=10+30 or 40
the probablity is 30/40 or 3/4 or 75% that you do not select a 5 dollar note
Finding the zeros using factoring and also the discriminat