150 V, dc motor drives a constant-torque load at a speed of 1200 rpm. The
armature and field resistances are 2 _ and 150 _, respectively. The
motor draws an armature current of 9 A and field current of 1 A. Assume that a
resistance is added in the field circuit to reduce the field current by 20%.
Calculate the armature current, motor speed, and value of the added resistance.