10 POINTS! Please explain to me how they got the answer? (there's an answer included)

http://www.flickr.com/photos/35618868@N0…


the correct answer is B. but I got A.

ok so the initial question is

V/r^2*h = 1/3

what does h equal to yield 1/3

multiply both sides by h
V/r^2 = h/3
multiply each side by 3
3V/r^2 = h

reinsert into the equation to see if your right

V/ r^2 (3V/r^2) = 1/3
the r^2 values cancel each other out
V/3V = 1/3
the V values also cancel each other out as well
1/3 = 1/3
the answer is B

(V/r^2h) = 1/3
multiply r^2h to both sides so,
v = 1/3 r^2h
now multiply the reciprocal of 3 on both sides so,
3v = r^2h
now divide r^2 to both sides so,
(3v/r^2) = h
there ya go :)

V/(r²h) = 1/3

Multiply both sides by 3h

h = 3V/r²

Basically, shift everything else to the right side, till you get 1/h=rsquared/3V. Then logically, invert the equation to give you h/1=3V/Rsquared

V / r^2h = 1/3
3V = r^2h
h = 3V / r^2

V/r^2h = 1/3

V = r^2h/3

3V = r^2h

h = 3V/r^2