if we take 86 to be the 100%
the decrease was 86 - 59, or 27
so, what is 27 of 86, in percentage?
well [tex]\bf \begin{array}{ccllll}
amount&\%\\
\textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\
86&100\\
27&x
\end{array}\implies \cfrac{86}{27}=\cfrac{100}{x}[/tex]
solve for "x"