there are "x" amount of cars in the lot, and oddly enough that's 100%, if we know that 60 is 40% of that, what is "x"?
[tex]\begin{array}{ccll} amount&\%\\ \cline{1-2} x & 100\\ 60& 40 \end{array} \implies \cfrac{x}{60}=\cfrac{100}{40}\implies \cfrac{x}{60}=\cfrac{5}{2} \\\\\\ 2x=300\implies x=\cfrac{300}{2}\implies x=150[/tex]