Moments of force question help!?

A meter stick is pivoted at its 50-cm mark but does not balance because of non-uniformities in its material that causes its center of gravity to be displaced from its geometrical center. However, when weights of 150 and 200 grams are placed at the 10cm and 75cm marks respectively, balance is obtained. The weights are then interchanged and balance is again obtained by shifting the pivot point to the 43-cm mark. Find the mass and the location of its center of gravity