A straight rod AB which is 60cm long, is in equilibrium when horizontal and supported at a point C, 10cm from A with masses of 6kg and 1kg attached to the rod at A and B respectively. It is also in equilibrium and horizontal when supported at another pivot at its midpoint, with masses of 2kg and 5kg attached at A and B respectively. Find the mass of the rod and the distance of the centre of gravity from A?