The dynamometer consists of a housing weighing ma and a metal spring weighing m, = 40 g A load weighing my = 100 g is suspended from the dynamometer hook. Dynamometer is pulled up with a force of F= 4 N. The dynamometer reading was 

F_d = 3 N. Determine the dynamometer housing weight m_d. Neglect the mass of the connecting wire between the spring and the load. Enter the answer in kilograms, rounded to the nearest hundredth.