Question

A plank AB 3m long weighing 20kg and with a centre of gravity 2m from the end A carries a load of mass 10 kg at the end It rests on two support at C and D 

Answer 1

$$(10)(9.8)(0.5)+R_D(1.5)=(20)(9.8)(1.5)\\R_D=163.3\ N$$

$$(10)(9.8)(2)=(1.5)R_C\\R_C=130.7\ N$$