well, we know they won 60% of the games, meaning 100% - 60% = 40%, they lost 40% of the games, and we also know that that number is 12.
[tex]\begin{array}{ccll} \%&amount\\ \cline{1-2} 40 & 12\\ 60& x \end{array} \implies \cfrac{40}{60}=\cfrac{12}{x}\implies \cfrac{2}{3}=\cfrac{12}{x} \\\\\\ 2x=36\implies x=\cfrac{36}{2}\implies x=18[/tex]