Double Pivots Question

A man is standing on a uniform plank of mass 20 kg and 6 m long. He is standing 1 m from the string at A.

a) Find the unknown forces FA and FB. (Ans: Fa = 550 N and FB = 250 N)

The man now walks to the left of A.

b) Determine the maximum distance in which the man can move before the plank topples. (Ans: d = 0.67 m)