The probability it will rain of Hari Merdeka is 2/15. Since you are finding the probability that will be no rain on Hari Merdeka, you also need to find the part of 15/15 that is not 2/15. You can do this by subtracting.
15/15-2/15=13/15.
The probability that will be no rain on Hari Merdeka is 13/15.
Then he slept 9 times. Because every hour is 60 minutes, since 1/3 of an hour is 20 mins, it should be 3 times per hour. So using basic math, 3 times 3 equals 9
