Answer:To find the common factors of the numbers and then reduce the sum to the lowest possible terms, let's consider the numbers: 5 and 15 Common factors of 5 and 15: - The factors of 5 are 1 and 5.- The factors of 15 are 1, 3, 5, and 15. Common factors: The only common factor of 5 and 15 is 1. Reducing the sum to the lowest terms: - The sum of 5 and 15 is 5 + 15 = 20.- Since there are no common factors other than 1, the sum cannot be further reduced. Therefore, the sum of 5 and 15, when reduced to the lowest terms, remains as 20.