$4.$ A site is underlain by two soil layers over bedrock. The unit weights of the top $($sand$)$ layer are $19$ and $21$ kN$/$m$3$ and the layer is $6$ meters thick. The unit weights of the bottom $($clay$)$ layer are $20$ and $22$ kN$/$m$3,$ and the layer is $8$ meters thick. The water table is located $2$ meters below the ground surface. The lateral stress ratio of the sand layer is $0\mathrm{.}4$ and that of the clay layer is $0\mathrm{.}5.$ Point A is located at a depth of $10$m$.$ Determine the magnitudes of the effective stress and the shear stress at point A$,$ on a plane oriented $12$ degrees clockwise from the horizontal plane. Important: you must use a compass to draw the Mohr Circle