Since the foci lie on x-axis. ∴ The equation of ellipse in standard form is $\frac{x^2}{a^2}+\frac{y^2}{b^2}$ = 1 We know that $c^2$ = $a^2-b^2$ ∴ $(4)^2$ = $a^2-(3)^2$ ⇒ $a^2$ = 16 + 9 = 25. Hence the required equation of ellipse is $\frac{x^2}{25}+\frac{y^2}{9}$ = 1.