A three phase $415 \mathrm{~V}, 50 \mathrm{~Hz}, \text { 6-pole, } 960 \text { RPM, 4 HP}$ squirrel cage induction motor drives a constant torque load at rated speed operating from rated supply and delivering rated output. If the supply voltage and frequency are reduced by $20 \%,$ the resultant speed of the motor in $\text { RPM}$ (neglecting the stator leakage impedance and rotational losses) is ________ (Round off to the nearest integer).