Aset s contains 6 elements, how many different subsets can be form the elements of s that will contain exactly 4 elements

The binomial coefficient express exactly the number of ways you can choose k elements from a set of n elements. It is defined as

where n! express the factorial of n, which is defined as the multiplication of all number from n to 2:

So, in your case, the number of subset of cardinality 4 that you can extract from a set of cardinality 6 is

d is the correct answer

step-by-step explanation:

x= 8 because 3x = 3 * 8, and 3*8 = 24