Answer
$$\frac{x^{2}}{16} + \frac{y^{2}}{25} = 1$$
Work Step by Step
$$25x^{2} + 16y^{2} = 400$$
Divide both sides by $400$.
$$\frac{25x^{2} + 16y^{2}}{400} = \frac{400}{400}$$ $$\frac{25x^{2}}{400} + \frac{16y^{2}}{400} = 1$$
Simplify:
$$\frac{x^{2}}{16} + \frac{y^{2}}{25} = 1$$
