How many total items are represented in a set of 15 apples and 20 oranges?

To find the total number of items in the set, you need to add the number of apples to the number of oranges. You have 15 apples and 20 oranges.

When you perform the addition:

15 (apples) + 20 (oranges) = 35 (total items).

Thus, the correct answer is 35, which reflects the total count of both types of fruit in the set. This approach to combining quantities is fundamental in basic arithmetic and ensures a clear understanding of how to aggregate separate groups to find a whole.