Answer:
6
Step-by-step explanation:
GCF=Greatest common factor
we know that it can not be 15 due to 15 not going into 54 due 54 not ending in a 5 or 0. and we know it cannot be 9 either due to 9 not going into 30
so it is 6 because 6 goes into 30 5 times and 6 goes into 54 9 times
Hope this helps
