Add all and divide by how many there is
answer is 5.08
Most likely number 3
we can guess the average of the two since we don't have the time to actually add all of them and divide and number 3 describes it the most
I think you just put 20 in the blank in order for it to equal
Answer:

Step-by-step explanation:
The mean is the sum of the allowances divided by the number of students.

Answer:
C
Step-by-step explanation:
The answer is C, because X is per year, so its 150 books per year, and the library already had is 7000 bc your adding that number to the amount of books your going to buy per year