well, let's see it this way, we know that 3000 is the 100%, and we also know that 3K is x% of 3000, so then
[tex]\begin{array}{ccll} amount&\%\\ \cline{1-2} 3000 & 100\\ 3K& x \end{array} \implies \cfrac{3000}{3K}=\cfrac{100}{x} \\\\\\ 3000x=300K\implies x=\cfrac{300K}{3000}\implies x=\cfrac{K}{10}[/tex]
