12. Which is a composite number? 99 b. 53 c. 57 d. 61 13. What is the greatest common factor of 14 and 28? 7 b. 9 c. 14 d. 28 14. How is 48 written as a product of its prime factors? 2x2x2x6 b. 2x2x2x2x2x3 15. What are the common factors of 16 and 24? a. 1,2,4. and 8 b. 1.2.3.4 and 8 c. 1,2, 3, 4, 5, 6, and 8 c. 2x3x6 d. 6x8 d. 1, 2 and 4