Answer:
A) there are 270.725 total of poker hands
B) there are 14.950 possible black flushes
C) the probability of being dealt a black flush is 0.0552220
Explanation:
Combinations gives the number of ways a subset of r elements can be chosen out of a set of n elements. Let's use the "n choose r" formula:

A) the total number of combinations of 4 cards chosen from the deck of 52 cards:
n = 52
r = 4

The 48! terms cancel

B) Number of possible black flushes:
There are 26 black cards (spades and clubs)
n=26
r=4

C) Probability of being dealt a black flush
Simply divide the result of B) over A)
