You need at least two terms to find a GCF.
4x
4c
6x3
3x
The GCF is a^2b
The GCF is 2x.
The GCF is 8x^3
27a3b2
The greatest common factor of 55 and 10 is 5.5 x 11 = 555 x 2 = 10
Take the greatest common factor of the first two numbers - for example, using Euclid's algorithm. Then take the greatest common factor of the result, and the third number, etc.
The GCF is 15x^2y^2
2 to the third power x2=highest common factor of 100 and 96=16