if we take 78 as the 100%, what's 11 of it?
well [tex]\bf \begin{array}{ccllll}
amount&\%\\
\textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\
78&100\\
11&x
\end{array}\implies \cfrac{78}{11}=\cfrac{100}{x}[/tex]
solve for "x"