if your dividing then 3 but if you want 21 sevenths as a mixed number then it would be 3.
Step-by-step explanation:
to find the quotient, you need to find out what multiplied by 7 gives you 21. (thats easy 3) so there is your answer. to find the mixed version of 21 sevenths you need to divide 21 by 7 ( literally what i just showed...) and you get 3.