A trapezoidal masonry retaining wall 1 m wide at top and 3 m wide at its bottom is 4 m high. The vertical face is retaining soil (φ = 30°) at a surcharge angle of 20° with the horizontal. Determine the maximum and minimum intensities of pressure at the base of the retaining wall. Unit weights of soil and masonary are 20 kN/m^{3} and 24 kN/m^{3} respectively. Suppose the coefficient of friction at the base of the wall as 0.45, Verify the factor of safety against sliding. Also determine the factor of safety against overturning.