The "g" in gcf stands for "greatest". The word greatest is a superlative adjective and that means that there can only be one GCF. So it makes no sense to ask what "are" the GCF.
GCF(15, 100) = 5.
The GCF is 5.
The GCF is 5.
The GCF is 5.
The GCF is 5.
5
15
The GCF is 5.
The greatest common factor of 15, 45 and 100 is 5.
The GCF of 15 and 90 is 15.
Since 15 is a factor of 60, it is automatically the GCF.
The GCF is 100.
The GCF is 15.