The soil conditions adjacent to a rigid frictionless retaining wall are shown in the figure below. A surcharge pressure of 50 kN/m2 is applied on the surface of the backfill. For Soil A above the water table, c' = 20 kN/m?, D' = 28, y = 18 kN/m3 For Soil B below the water table, c' = 0, O' = 38, y = 20 kN/m3 Calculate the maximum Rankine active earth pressure behind the wall and the resultant active force per unit length of the wall. Also determine the location of the resultant force. q = 50 kN/m2 Soil A 6 m GWT 3 m Soil B 77