A $220$ V d$.$c series motor has armature and field resistances of $0\mathrm{.}15$ and $0\mathrm{.}10$ respectively. It takes a current of $30$ A from the supply while running at $1000$ rpm $.$ If an external resistance of $1$ is inserted in series with the motor, calculate the new steady state armature current and the speed. Assume the load torque remains constant.