A box is filled with 9 yellow cards, 3 green cards, and 3 brown cards. A card is chosen at random from the box. What is the probability that it is a yellow or a brown card? Write your answer as a fraction in simplest form.

Here is what we know ...

There is a total of 15 cards

Adding brown and yellow cards together is 12/15 cards

The probability of picking a brown or yellow card is 12/15 since there are 12 yellow and brown cards and a total of 15 cards. You still need to simplify this though.

12 and 15 can both be divided by 3 (12/15)

12 divided by 3 = 4

15 divided by 3 = 5

This simplifies into 4/5

The probability that a yellow or brown card is chosen from the box is 4/5