b) A gasoline engine is specified to be 4-stroke and four-cylinder. It has a bore of 80 mm and a stroke of 100 mm. On the test, it develops a torque of 75 N.m when running at 3000 rpm. If the clearance volume in each cylinder is 60 cm^3, the relative efficiency is 0.5, and the calorific value of the fuel is 42 MJ/kg, determine the brake thermal efficiency.