Respuesta :
answer: 7
explanation: The GCF is the greatest number that can go into both numbers equally. 7 can go into both, since 7 is 7 and 21 is 7 x 3. Therefore, 7 is your greatest common factor.
explanation: The GCF is the greatest number that can go into both numbers equally. 7 can go into both, since 7 is 7 and 21 is 7 x 3. Therefore, 7 is your greatest common factor.