Answer :
[tex]\sf \frac{33,5x}{100}=21 \\ \\ 33,5x=2100 \\ \\ \boxed{\sf x=62,6\%}[/tex]
[tex] \frac{x}{100} = \frac{21}{35.5} [/tex] Multiply 33.5 to 100 then divide the answer to 21, and the answer would be about 62.39 %