Answer:4
Step-by-step explanation:The GCF of 12 and 28 is 4. To calculate the GCF (Greatest Common Factor) of 12 and 28, we need to factor each number (factors of 12 = 1, 2, 3, 4, 6, 12; factors of 28 = 1, 2, 4, 7, 14, 28) and choose the greatest factor that exactly divides both 12 and 28