well, the original price was "x", which is of course the 100%, the new price is 10% less than that, or namely 90% of that original and we know is 200 bucks.
[tex]\begin{array}{ccll} amount&\%\\ \cline{1-2} x&100\\ 200&90 \end{array}\implies \cfrac{x}{200}=\cfrac{100}{90}\implies \cfrac{x}{200}=\cfrac{10}{9} \\\\\\ 9x=2000\implies x=\cfrac{2000}{9}\implies x=222.\overline{2}[/tex]
