$$\left. \begin{array} { l } { [ T ] + [ T ] = 13 } \\ { \frac { E } { 13 } - \frac { 1 } { 13 } = 6 } \end{array} \right.$$
$T = \frac{13}{2} = 6\frac{1}{2} = 6.5$
$E=79$
