The $Y_{\text{bus}}$ matrix of a two-bus power system having two identical parallel lines connected between them in pu is given as $$Y_{\text{bus}} = \begin{bmatrix} -j8 & j20 \\ j20& -j8 \end{bmatrix}$$The magnitude of the series reactance of each line in pu  (round off upto one decimal place) is__________.