Magnitude and Flux (Astrophysics)?

I see how you got to where you did. It looks like you made one small mistake though. The logarithm is a base 10, not base e so you should have 10^22/5. Other than that though, you did just what you should have. There isn't enough information to know by how much the flux increased. You need at least one more piece of information. Either you need the value of the constant, or you need one of the two fluxes. Without those, this problem is not possible to do. It may be though that your teacher simply wants the difference of the log of the fluxes. Often in astronomy (and physics in general) one works with the logs of numbers rather than the numbers themselves because it is simpler to work with them being that they're smaller. So either a piece of information has been left out, or you're supposed to give the difference in the log of the fluxes.