First we can divide 12,000 by 10 to get 10% of it: 1,200. Then we multiply it by 4 to get 40%: 4,800. Next we add 12,000 to 4,800: 16,800. He spent $16,800 on advertising during the second year, hope this helps!
Since its out of 15 marbles all together and all you need to find is the probability of 3 blue marbles you would have to divide 3 by 15. The outcome would be 0.2 or in your case... B. - 0.20