$11-7.$ What is the total active earth pressure per foot of wall for the retaining wall in Problem $11-4,$ with an angle of wall friction between backfill and wall of $25,$ using Coulomb theory?

$11-7$a$.$ Assume that the base of the wall is $4$ feet wide, and the wall is constructed of reinforced concrete $($unit weight of $150$ pounds per cubic foot$).$ Using the same angle of friction between the backfill and the wall as the friction between the bottom of the wall and the underlying soil $($assume the same soil parameters shown in Figure $11-39),$ determine the Factor of Safety of the Retaining Wall for

SLIDING and OVERTURNING.

PLEASE SOLVE PROBLEMS $11-7$ AND $11-7$a ONLY!! Thank you!!