since we know that 36 is the 80%, how much is the 100% anyway?
[tex]\bf \begin{array}{ccll} amount&\%\\ \cline{1-2} 36&80\\ x&100 \end{array}\implies \cfrac{36}{x}=\cfrac{80}{100}\implies \cfrac{36}{x}=\cfrac{4}{5} \\\\\\ 180=4x\implies \cfrac{180}{4}=x\implies 45=x[/tex]
