7. A uniform meter stick (100 cm) is loaded with the following masses: 110 g at 15.0 cm, 140 g at 60.0 cm, and 180 g at 90.0 cm. It was found that the center of gravity (balance point) of the system was at 59.4 cm. Assuming that the system is in both translational and rotational equilibrium, what is the mass of the meter stick?