A separately excited $\text{DC}$ motor rated $400 \mathrm{~V}, 15 \mathrm{~A}, 1500\mathrm{~ RPM}$ drives a constant torqueload at rated speed operating from $400 \mathrm{~V}$ $\text{DC}$ supply drawing rated current. The armature resistance is $1.2 \Omega.$ If the supply voltage drops by $10 \%$ with field current unaltered then the resultant speed of the motor in $\mathrm{~ RPM}$ is_________ (Round off to the nearest integer).