1. **State the problem:** Find the factors of 324 that add up to 15. 2. **Find the factors of 324:** 324 can be factored into pairs: - 1 and 324 - 2 and 162 - 3 and 108 - 4 and 81 - 6 and 54 - 9 and 36 - 12 and 27 - 18 and 18 3. **Check sums:** We need a pair whose sum is 15: - 1 + 324 = 325 - 2 + 162 = 164 - 3 + 108 = 111 - 4 + 81 = 85 - 6 + 54 = 60 - 9 + 36 = 45 - 12 + 27 = 39 - 18 + 18 = 36 None of these pairs add up to 15. 4. **Check individual factors that could sum to 15:** Consider two factors separately whose sum is 15: Look at divisors less than 15: 1, 2, 3, 4, 6, 9, 12 Check pairs: - 6 + 9 = 15, and both 6 and 9 are factors of 324. **Answer:** The factors of 324 that add up to 15 are $6$ and $9$.