In this question use $g=9.8$ m s${}^{-2}$.

A uniform beam $AB$ of length 10 m is supported by a pivot at its midpoint. An object of mass 16 kg is placed at the end $A$. A second object of mass 20 kg is placed on the beam at a distance $w$ m from the pivot, on the opposite side of the pivot from $A$, so that the beam rests horizontally in equilibrium.