she surveyed "x" amount, which is the 100%, but we also know that 180 is the 37.5%, so
[tex]\bf \begin{array}{ccll} amount&\%\\ \cline{1-2} x&100\\ 180&37.5 \end{array}\implies \cfrac{x}{180}=\cfrac{100}{37.5}\implies 37.5x=18000 \\\\\\ x=\cfrac{18000}{37.5}\implies x=480[/tex]