Respuesta :
the gcf of 9 & 21 is 3 so 9 in simplest form is 3 & 21 is 7
the greatest common factor (GCF) between 9 and 21 is 3 cuz 3²=9 and 3 ×7 =21band if you add them together you get 30 and the greatest common factor between all three numbers is 3