David Gwyn J. answered 11/30/20
Highly Experienced Tutor (Oxbridge graduate and former tech CEO)
The standard equation for an ellipse is (x - h)² / a² + (y - k)² / b² = 1
where horizontal radius = a, vertical radius = b and center = (h, k)
We are given end points of the axes:
horizontal axis (because y coordinate is same) is (-12, -8) to (2, -8)
=> x diff = 2 - -12 = 14 => a = 14/2 = 7 and h = -12 + 7 = -5
vertical axis (because x coordinate is same) is (-5, -13) to (-5, -3)
=> y diff = -3 - -13 = 10 => b = 10/2 = 5 and k = -13 + 5 = -8
hence equation is (x - -5)2 / 72 + (y - -8)2 / 52 = 1
=> (x + 5)2 / 49 + (y + 8)2 / 25 = 1 or 25(x + 5)2 + 49(y + 8)2 = 1225, if you prefer
You can double-check the points and equation on Desmos Graphing or similar.