6. A meter stick is placed on a pivot with three masses attached so that it is balanced. The meter stick has a mass of 85 g and its center of gravity is at the 50 cm mark. The pivot is placed under the 50 cm mark on the meter stick. A 75 g mass is hung from the 40 cm mark on the meter stick and a 20 g mass is hung from the 90 cm mark. Where would a 7.5 g mass be placed to balance the meter stick? 40cm 50cm 75g 90cm 20g