Since you want to find the numbers that has 33x__ as the highest, I believe 66, and 99 should work.
The GCF of the given numbers is 3
It is: 1
33 and 77 have a GCF of 11 and an LCM of 231.
9 and 126
479 and 958 have a GCF of 479.
4 and 8
You need at least two numbers to find a GCF.
The GCF of 90 and 180 is 90.
You need at least two numbers to find a GCF.
The GCF is, yes.
The GCF will, yes.
The GCF of 60 and 120 is 60.