Well. add all of these up 8+5+5. we know 5+5 is 10. and 10+8 is 18. so 18 is the denominator. There are 8 red markers and 5 blue markers at 8 and 5 up. 8+5 is 13 right? So the numerator will be 13. but the probability of picking a blue then a red is 13 alone or if you are ask for out of the amount of markers there are, its 13/18. so the probability is 13 or 13/18.
