1. **State the problem:** Find the sum of all even numbers from 5 to 15. 2. **Identify the even numbers in the range:** The even numbers between 5 and 15 are 6, 8, 10, 12, and 14. 3. **Use the formula for the sum of an arithmetic series:** The sum $S$ of $n$ terms of an arithmetic sequence with first term $a_1$ and last term $a_n$ is given by $$S = \frac{n}{2}(a_1 + a_n)$$ 4. **Count the number of terms:** The even numbers are 6, 8, 10, 12, 14, so $n = 5$. 5. **Calculate the sum:** $$S = \frac{5}{2}(6 + 14) = \frac{5}{2} \times 20 = 5 \times 10 = 50$$ 6. **Final answer:** The sum of all even numbers from 5 to 15 is $50$.