Question:
A bag contains 5 red, 8 green and 7 white balls, One ball is drawn at random from the bag. What is the probability of getting a white ball or a green ball?
Solution:
GIVEN: A bag contains5 red, 8 green and 7 white balls
TO FIND: Probability of getting a white ball or a green ball.
Total number of balls 
Total number of green or white balls 
We know that PROBABILITY = 
Hence probability of getting a green or a white ball = 
Hence probability of getting an green or white ball = 