A direct tensile stress $$x $=160$ MN$/$m$2$ and a direct compressive stress

$$y $=-120$ MN$/$m$2$ are applied at a particular point in an elastic material on

two mutually perpendicular planes. The maximum principal stress in the

material is limited to $200$ MN$/$m$2$

$($in tension$).$ Use Mohr$$s circle to find the

allowable value of shear stress at the point.