namely, if 800 is the 100%, what is 160 in percentage of it?
[tex]\bf \begin{array}{ccllll}
amount&\%\\
\textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\
800&100\\
160&x
\end{array}\implies \cfrac{800}{160}=\cfrac{100}{x}[/tex]
solve for "x"