First, subtract both sides by 25:
x^2 - 6x = -25
Because we're completing the square, we subtract both sides by 9:
x^2 - 6x - 9 = -34
(x - 3) = 5.831 (about)
x = 8.831

<u>Step-by-step explanation:</u>
The ellipse is vertical so y has the biggest radius.
Major axis (y) = 20 so the y-radius is 20/2 = 10
Minor axis (x) = 14 so the x-radius is 14/2 = 7
The equation of an ellipse is:
where
- (h, k) is the center of the ellipse
- a is the x-radius
- b is the y-radius
Given: a = 7, b = 10
Assume: (h, k) = (0, 0)

I made this graph for you- the red is the 80%, and the green is the leftover 20%.
Answer:
18.72 cubic feet
Step-by-step explanation:
Volume of the aquarium = lwh
- l = 5.2 ft,
- w = 1.8 ft
- h = 2 ft
V = 5.2*1.8*2 = 18.72 cubic feet