Hi
Standard Form of an Equation of an Ellipse is
where Pt(h,k) is the center and a and b are the respective vertices distances from center.
foci: (+9,0) major axis along the x=axis
major axis of length: 24 2a = 24 a = 24/2 = 12
f = sqrt(144-b^2) = 9b^2 = 63