Yes, the amount of substance (n) = m/M so you have 3 grams of methanol, the n = 3/32 = 0.09375 moles. So 0.09375 moles was consumed. The energy released was 1045 Joules. The enthalpy of combustion is the enthalpy change per mole of substance, so in order to find this, multiply 1045 by 32/3 or 1/0.09375. So you get enthalpy of combustion as -11140 J mol-1 or -11.14 kJ mol-1