2 questions of moment

1. A uniform rod AB of length 5m and mass 6kg is pivoted at C where AC=1.5m. Calculate the mass of the particle which must be attached at A to maintain equilibrium with the rod horizontal.

2. A uniform beam AB of length 4m and mass 21 kg has a particle of mass 15kg attached at A and a particle of mass 18kg attached at B. The beam is balanced horizontally on a single support at C. Find the distance AC.