Probability of drawing a red ball is 3/5. Do you know why? What is the probability of drawing a yellow ball?

There are three ways to retrieve 2 red and 1 yellow ball. In order of the balls appearance out of the bag:

r-r-y, r-y-r, y-r-r

Probability you are looking for is the sum of the probabilitles of these three events.

The probability of each of these is the product of probabilities of drawing a ball of a given color.