Answer:
6
Step-by-step explanation:
We know if we multiply 6x2=12 and 6x5=30. After 6 you can not multiply anything else higher than that. For example 15x2=30 but 15 is not a GCF of 12 and 4x3=12 3 and 4 are not GCFs of 30. So 6 is the GCF of 12 and 30.
