An $LPF$ wattmeter of power factor $0.2$ is having three voltage settings $300 V$, $150 V$ and $75 V$, and two current settings $5 A$ and $10 A$. The full scale reading is $150$. If the wattmeter is used with $150 V$ voltage setting and $10 A$ current setting, the multiplying factor of the wattmeter is _________.