A $9\mathrm{.}0$ m high MSE wall is constructed with sandy soil having a friction angle of $25$ degrees

and a total unit weight of $17\mathrm{.}6$ kn$/$m$3$

$.$ The wall rests on and retains soil having a friction

angle of $20$ degrees and a unit weight of $19\mathrm{.}2$ kn$/$m$^3$

$.$ The minimum length of

reinforcement is $70\%$ of the height of the wall. The friction coefficient between the MSE wall

material and the soil in the field is $0\mathrm{.}414.$

a$)$ What is the factor of safety against sliding?

b$)$ What is the factor of safety against overturning?

c$)$ If these factors are not adequate, what do you recommend?