We first need to find out the total amount of ounces of soup he has.
1 container = 18 ounces
6 containers = x
Where x is the total amount of ounces in 6 containers.
Cross multiplying the above equation we get:
1 * x = 6 * 18
x = 108
Total amount of soup he has is 108 ounces.
We now simply divide this by the number of people, so:
108 / 9 = 12
So each person will get 12 ounces of soup.
