The calorific value of the fuel is 3,000 kJ/kg

Amount of fuel burnt = 60 kg
Amount of heat produced = 1,80,000 kJ
Calorific value of the fuel =  Heat produced /Amount of fuel 
                                                  = 1,80,000/ 60 

                                                  = 3,000 kJ/kg
∴ Calorific value of the fuel is 3,000 kJ/kg.