Question

when a boy weighing 20 kgf sits at one end of a 4 m long see saw it depresses at this end. how can it be brought to the horizontal position by a man weighing 40kgf.

Answer 1

let man sits at position x from centre
so 20 ×2 = 40 ×x
x =1m away from centre

Answer 2

Here it is . I hope you understand