Answer:
The GCF is going to be 30
Step-by-step explanation:
This Is how I find the GCF of 2 numbers. I find the prime factorization first, then I find the common factors and multiply them. Here
The prime factorization of 21, 2 × 3 × 3 × 5= 90
The prime factorization of 28, 2 × 3 × 5 × 7 = 210
The common factors are, 2, 3, and 5. We multiply those to get the GCF.
2 × 3 × 5 = 30
