let's say "x", therefore, "x" is the 100% then, and 16 is the 40% of it.
[tex]\bf \begin{array}{ccll}
amount&\%\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
x&100\\
16&40
\end{array}\implies \cfrac{x}{16}=\cfrac{100}{40}\implies x=\cfrac{16\cdot 100}{40}[/tex]
