For the parabola of this form (intersecting the x-axis at two points and opening downwards), the general form would be:
(x - h)² = -4a(y - k)
where
the vertex has coordinates (h,k)
From the figure, the vertex is at (50,150). Using one point which is at (0,0), we can determine a and complete the form:
(0 - 50)² = 4a(0 - 150)
-4a = 50/3
Thus, the complete formula is
(x - 50)² = -50/3(y - 150)
