Answer:
30
Explanation:
If we have 4 integers that have an average of 9, then all the numbers will add up to
.
If we want the greatest number possible, the other 3 need to be the lowest possible.
Since they are all different, the lowest possible values of the first 3 numbers are 1, 2, and 3.


So 30 is the greatest value of one of the integers.
Hope this helped!