The average of a certain set of numbers is the quotient when the sum of the numbers is divided by the count of the numbers present. In the problem above, there are five numbers including x. The sum of these numbers may be obtained by multiplying 16 by 5 which gives 80. Thus,
20 + 20 + 19 + 13 + x = 80
This equation gives a value of x equal to 8.
Thus, the answer is letter B. 8
