so.. we took 1/3 that was in the teapot, dumped it into the container, and the container ended up 2/3 of the way, now, to fill the container, all we need is really 1/3, because 2/3 + 1/3 is 3/3 or 1 whole
so.. how much is 1/3 of the container, in teapot's terms?
well [tex]\bf \begin{array}{ccllll}
teapot&container\\
\textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\
\frac{1}{3}&\frac{2}{3}\\\\
x&\frac{1}{3}
\end{array}\implies \cfrac{\frac{1}{3}}{x}=\cfrac{\frac{2}{3}}{\frac{1}{3}}
\\\\\\
\cfrac{\frac{1}{3}\cdot \frac{1}{3}}{\frac{2}{3}}=x\implies \cfrac{\frac{1}{9}}{\frac{2}{3}}=x\implies \cfrac{1}{9}\cdot \cfrac{3}{2}=x\implies \cfrac{1}{4}=x[/tex]