I don't know if this is correct or not but I don't think it can be factored any further. If it can, it would probably be something related to 7. Sorry if I didn't help
The GCF is the greatest common factors of the numbers available.
First, We write the factors of 21 m and 49n, 21m = 3*7*m And , 49n = 7*7*n Now the common factors of 21m and 49n are: 7. So, the greatest common factor will be 7
