Step 1. Convert the 10 1/2 cups to a fraction:

10 1/2 cups is equal to 21/2 cups
Step 2. Divide the total of cereal in the box 21/2 by the cups per serving:

To make this division we follow the rule to divide fractions:

We apply this to our division:

solving the multiplications:

How many servings in a box? Answer: 14