Redox Reactions and Electrochemistry: JEE Main 2009 Chemistry question

In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is CH₃OH(l) + 3/2O_2 $\to$ CO₂ (g) + 2H₂O (l) At 298K standard Gibb’s energies of formation for CH₃OH(l), H₂O(l) and CO₂ (g) are -166.2, -237.2 and -394.4 kJ mol⁻¹ respectively. If standard enthalpy of combustion of methanol is -726 kJ mol⁻¹, efficiency of the fuel cell will be