I am honestly lost here, so any help would be greatly appreciated.

Consider a reactor making use of U-235 fuel. Assume it has an operational efficiency of 30% (meaning for every unit of thermal energy generated, 0.30 units actually become electrical energy) and has 2000 kg of U-235 to burn through. How long could this reactor provide electricity to (550 GW- hr per month usage) before refueling? For U-235, take the average thermal release of 180 MeV/fission