The answer above is mostly correct, HOWEVER The ellipse is a vertical ellipse and therefore uses the equation (x^2/b^2)+(y^2/a^2)=1
a=10/2=5
b=8/2=4
put it in the equation and it is (x^2/4^2)+(y^2/5^2)=1
Simplify and the answer is (x^2/16)+(y^2/25)=1