Final answer:
The greatest common factor (GCF) of 36 and 9 is 9. Using the GCF, we can factor 36 - 9 as 27.
Step-by-step explanation:
(a) To find the greatest common factor (GCF) of 36 and 9, we need to find the largest number that divides evenly into both 36 and 9. The prime factors of 36 are 2 x 2 x 3 x 3, while the prime factors of 9 are 3 x 3. The common prime factor is 3 x 3, which is equal to 9. Therefore, the GCF of 36 and 9 is 9.
(b) Using the GCF of 9, we can factor 36 - 9 as follows: 36 - 9 = 9(4 - 1) = 9(3) = 27.