As written, the GCF is 6. If that's 15, 42 and 84, the GCF is 3.
The GCF is 42.
The GCF of 42 and 84 is 42.
The GCF is 7.7 is the GCF of 42, 49 and 84.
The GCF is 6.
The GCF is 6.
The GCF is 6.
The GCF is 7.
The GCF is 21.
The GCF is: 3
GCF(42, 63, 84) = 21.
The GCF is 42.