Answer:
Step-by-step explanation:
If you are asking for the Greatest Common Factor [GCF], then here you go. All coefficients are divisible by 9...:
63: 1, 7, 9, 63
27: 1, 3, 9, 27
18: 1, 2, 3, 6, 9, 18
...and you take the LEAST DEGREE TERM POSSIBLE.
I am joyous to assist you anytime.