If the center is at (0, 0) and the vertex is at (20, 0), then the distance, a, is the length from the center to the vertex, 20. The distance from the center to the focus is c. The distance from the center to the focus is 16, so c = 16. The formula we use to find the focus is

. We have our c value and our a value, so we will sub in those to find b.

and 256 = 400 - b^2. -b^2 = -144, so b = 12. There you go!
Answer:
anything raised to the power of zero= 1
(1+1/4^½)²
(1 + 1/2)²
(3/2)²
9/4
=2.25
The B option is the correct answer
Let Xavier's favourite fraction be a/b, Yessie's favourite fraction = b/a and Zorro's favourite fraction = c/d,
c/d x a/b = 12/35 . . . . . . . . (1)
c/d x b/a = 15/7 . . . . . . . . (2)
(1) x (2) = c/d x a/b x c/d x b/a = 12/35 x 15/7
c^2 / d^2 = 36/49
c^2 = 36
c = 6
d^2 = 49
d = 7
Xaviers favourite fraction = 12/35 / 6/7 = 2/5
Yessies favourite fraction = 5/2
Zorro favourite fraction = 6/7
2/8 and 4/16 are equivalent to 1/4