Remark
The general equation for an ellipse is
At the center, the the point is 0,27
Solving for the

or b^2= 27^2 * 1
Taking the square root of both sides
b = 27
Now we need to use one more piece of information
The second point is (24,9) what that means is at the point x = 24, y = 9
Solving for that

576/a^2 + 81/729 = 1 Subtract 81/729 from both sides
576/a^2 = 1 - 81/729 = 576/a^2 = (729 - 81)/729 = 648 /729
576/a^2 = 648/729 Cross multiply
648 a^2 = 729 * 576 Divide by 648
a^2 = 648
Full equation for the ellipse and answer is
d i believe so it might be d if not i’m sorry
Answer:
Your answer would be 70.434! Sorry if its wrong, but im sure its right!
I'd wait for somebody else to answer just to confirm!
Let's just start with x=20 and then do some algebra to it to make it all complicated
x = 20
2 * x = 2 * 20
2x = 40
2x - 13 = 40 - 13
2x - 13 = 27