Question

you are trying to balance a tray of dishes to make it easy to carry. at one end of the 0.6m tray are four plates with total mass 0.5 kg with their centres of mass exactly above the left edge of the tray. how far from the left edge should you place 2.1 kg jug of milk so that the centre of mass of the system is at the centre of the tray?

Answer 1

Balance the torques:
4*(.5)*9.8*.3 = 2.1*9.8*x
you can cross the 9.8 to simplify