The DC shunt motor is running at full load with a supply voltage of 440 V and a supply current of 70 A. The rotation speed in full load is 1000 rpm, the field resistance is 200 Ohm and the armature resistance is 0.2 Ohm. Calculate its speed if the load torque is reduced to three-fourth of the full-load torque, and the armature resistance is increased by 0.5 Ohm. Neglect the voltage drop due to the brushes and assume constant flux.