Your initial going-about the problem is a good start, however, I would make sure that you understand what the ΔT in your equation signifies.
Okay, once you've recognised that, from where you're at, what do you think you'll next need to consider? You're told to find how many grams of cyclohexane will need to be burned to give off this amount of heat. What data are you given about cyclohexane?
XeLa