Answer:
16
Explanation:
So if 4 numbers have an average of 14, that means to find the sum of all 4 numbers, you work backwards & multiply 4x14 to get 56.
Then 56-the sum of the 3 numbers you already have (11+12+17=40)
56-40=16
To double check, to find the average of 4 numbers that total 56, you divide 56 by 4 & get 14