When operated from a $300-$V dc supply, a dc series motor operates at $1225$ r$/$min with a line current of $70$ A$.$ Its armature$-$circuit resistance is $0\mathrm{.}13$ and its series$-$field resistance is $0\mathrm{.}09.$ Due to saturation effects, the flux produced by an armature current of $25$ A is $54$ percent of that at an armature current of $70$ A$.$ Find the motor speed when the armature voltage is $300$ V and the armature current is $25$ A$.$