1. The problem is to find the sum of the numbers 28 and 81.76. 2. The formula for addition is simply $a + b$ where $a$ and $b$ are the numbers to add. 3. Applying the formula: $$28 + 81.76$$ 4. Adding the numbers: $$28 + 81.76 = 109.76$$ 5. Therefore, the sum of 28 and 81.76 is $109.76$.