let's say "x" is the whole lot and thus the 100%.
we know 12 is 60%, how much is "x" or 100%?
[tex]\bf \begin{array}{ccll} amount&\%\\ \cline{1-2} x&100\\ 12&60 \end{array}\implies \cfrac{x}{12}=\cfrac{100}{60}\implies \cfrac{x}{12}=\cfrac{5}{3} \\\\\\ 3x=60\implies x=\cfrac{60}{3}\implies x=20[/tex]
