if we take 4100 to be the 100%, what is 870 off of it in percentage?
[tex]\bf \begin{array}{ccll} amount&\%\\ \cline{1-2} 4100&100\\ 870&x \end{array}\implies \cfrac{4100}{870}=\cfrac{100}{x} \\\\\\ 4100x=87000\implies x=\cfrac{87000}{4100}\implies x=\cfrac{870}{41}\implies x\approx 21.22[/tex]
