I think it’s 1.7444921e+26
The answer to this problem would be 700. if you need the sum that isnt estimated, its 678.
1) We have that there are (52,3) ways to pick 3 cards out of 52 cards. Also, there are (4,3) ways to pick 3 kings out of the 4 total available kings in the deck. In essence, we need to have one of those ways to be the selected 3 cards. Hence, the probability is the ration (4,3)/(52,3). Computing this:
P=

The probability is very low but not negligible.
2) The Pascal triangle defines a recursive relationship. Hence, we would need to calculate all the binomial coefficients up to 51. Thus, it is not at all practical to use the Pascal Triangle to calculate the ways. It is easier to do the direct computation.
The answer is A because if you make up an age for Julia for example Julia is 6 years old. In that case we multiply her age by 3 to figure out Henry's age which is 18. Rhianna is half as old as Julia is so that would make her 3 years old. In order for Henry which he is 18 years old to get to Rhianna's age which is 3 years old. you just divide 18 by 3 which is 6 years old. therefore the answer is A