1. **State the problem:** Calculate the sum of 5 and 10. 2. **Formula used:** Addition of two numbers is given by $a + b$. 3. **Apply the formula:** Here, $a = 5$ and $b = 10$, so we calculate: $$5 + 10$$ 4. **Perform the addition:** $$5 + 10 = 15$$ 5. **Final answer:** The sum of 5 and 10 is 15.