A series LCR circuit is connected to an $AC$ source of $220 V , 50 Hz$ The circuit contains a resistance $R =80 \Omega$, an inductor of inductive reactance $X _{ L }=70 \Omega$, and a capacitor of capacitive reactance $X _{ C }=130 \Omega$ The power factor of circuit is $\frac{x}{10}$ The value of $x$ is :