Hi again Kath;
According to my college physics professor, E=mc^{2 }is an oversimplification of the mathematical formula. The way E=mc^{2} has been taught in the grammar schools drove him crazy.
Unfortunately, I no longer have my college notes. I researched this on the internet. In its original form, the formula is ...
E^{2}=[(m^{2})(c^{4})]+[(p^{2})(c^{2})]
E=energy of the particle
m=rest mass
p=momentum, also represented as mass multiplied by velocity, (mass)(velocity), p=mv.
c=speed of light, 299,792,458 meters per second.
If the mass is not moving, then p, momentum, is zero, because velocity (speed and direction of motion) is zero...
E^{2}=[(m^{2})(c^{4})]+[(0^{2})(c^{2})]
Then this is...
E^{2}=m^{2}c^{4}
The square root of both sides is...
E=mc^{2}
As William explained, this can also be represented as...
c=√(E/m) or c=(E/m)½
As to the original equation, I do not know of any way of isolating c as the subject.
I know this does not answer your question. I just want to ask of you not to drive your college professors crazy.
11/29/2013

Vivian L.
Comments
Then tell me the meanings of each equation and which one they think is the "real" equation.
E = mc2 <= the mass of the universe and speed of light determine how much energy is in the universe.
m = E/c2 <= the energy in the universe and speed of light determine how much mass there is
c = √(E/m) <= the ratio of energy to mass in the universe determines the sped of light