$\begin{array}{1 1}\frac{x^2}{64}+\frac{y^2}{100}=1 \\ \frac{x^2}{16}+\frac{y^2}{36}=1 \\ \frac{x^2}{64}+\frac{y^2}{36}=1 \\ \frac{x^2}{100}+\frac{y^2}{64}=1\end{array} $