The new equation is
<em>Y = (x-8)² </em>.
The other way to write it is like this: (you might not recognize it in this form)
Y = x² - 16x + 64
(2^6)^x=1
(4)^x=1
(4)^0=1
1=1
X=0
(5^0)^x=1
(1)^x=1
x=(-∞,∞)
X is always dependant to Y. so that should answer the 1st one. the 2nd looks to be around 17-18. 17.5 maybe. and the 3rd is yes cause he does not go to the pool so it isnt any cost.
The formula is V=Bh
You'd get the base (it's a circle so you'd have to do A=pie*radius square)
Once you find the base, you mutliply it by the height