Question

A woman of mass m = 55 Kg sits on the left edge of a plank oflength L = 4 m and mass 12 Kg (she is sitting 2 meters to the leftof the center of the plank). The Plank is pivoted at a point thatis 0.5 meters to the left of the center of the plank (this meansthat the fulcrum is 0.5 meters to the left of the center of theplank)
a) Where should a man of mass M = 75 Kg sit if the system (plankplus man and woman) is to be balanced?
b) Find the normal force exerted by the pivot on the plank.