Problem $5)$ The soil behind the retaining wall is composed of two layers. The top layer is a sand with an effective angle of friction of $\backslash$phi $^\text{'}=19^$ and the bottom layer is an over$-$consolidated clay. A newly$-$built structure on top of the soil introduces a surcharge of $250$ psf$.$ The undrained cohesion of the clay is c$\_$u$=45$ psf$.$ Calculate the lateral forces from just the soil on the right side of the wall. $(20$ pts$.)$