Respuesta :

4/7 because if you simplify 12/21 by 3 , you'll get 4/7
Now, we have this expression:
x/y
Now put all the njmber that I had into this expression:
x/y
=12/21
Now, this is not simplify yet
Divide 3
12/3/21/3
=4/7 is your final answer. Hope it help!