I m not sure about my ans.
Step-by-step explanation:
[tex]21 = 3 \times 7 \\ \\ 84 = 2 \times 2 \times 3 \times 7 \\ \\ common \: factors \: = 3 \: and \: 7 \\ \\ \therefore \: hcf \: of \: 21 \: and \: 84 = 3 \times 7 = 21[/tex]
