We have:
1 box has 6 cups
and 1 serving is 1/5 of 1 cup
Then:
Since there is 1/5 of a cup of oatmeal in a serving, this means that each of the 6cups contains 5 servings.
The total number of servings is seen to be

as there are 6 groups of 5 servings
Answer: 30