A vane shear test was conducted in a saturated soft clay, using a 100 mm x 200 mm vane. When the vane was rotated at the standard rate of 0.1°/s, the torque measured in the torque meter increased to 60 N ? m, and with further rotation reduced to 35 N ∙ m. Determine the peak and residual undrained shear strengths of the clay.