For the construction of a highway. A cut is to be made as shown in the figure.
The soil exhibits c'= 20kPa, =18 °, and the undrained shear strength = 80 kPa. The unit weight of water is 9.81kN/m³. The unit weights of the soil above and below the ground water table are 18 and 20 kN/m³, respectively. If the shear stress at Point A is 50 kPa, the factors of safety against the shear failure at this point, considering the undrained and drained conditions, respectively, would be