An alternator with internal voltage of $1\angle \delta _{1}\text{p.u}$ and synchronous reactance of $\text{0.4 p.u}$ is connected by a transmission line of reactance $\text{0.1 p.u}$ to a synchronous motor having synchronous reactance $\text{0.35 p.u}$ and internal voltage of $0.85\angle \delta _{2}\text{p.u}$.
If the real power supplied by the alternator is $\text{0.866 p.u}$, then $\left( \delta _{1} -\delta _{2}\right)$ is _________ degrees. (Round off to $2$ decimal places.)
(Machines are of non-salient type. Neglect resistances.)