You fail MAJORLY at basic re-arranging of equations, and everyone else in this thread fails to varying degrees as well.
r*24 = 0
divide both sides by 24:
r = 0/24
r=0
If you can't understand that then I suggest you go back and redo third grade.
As for the undefined/infinity discussion:
A quantity x/0, x real, is
undefined. To see why, look at the left and right limits of the function y=1/x as x approaches 0. The left limit will give you -infinity, and the right limit gives +infinity. Thus, the limit does not exist, and 1/0 is undefined in the reals. It's not a rigorous proof, it just demonstrates why 1/0 is not infinity.
I suggest you
ALL read this:
http://en.wikipedia.org/wiki/Divide_by_zero