$(10$ points$)$ A balanced $Y-Y$ distribution system has a line impedance of $0\mathrm{.}6+j0\mathrm{.}3$ and a load impedance of $10+j15$ per phase. The per phase power loss on the line is $60$ W $.$

$($a$)$ Find the per$-$phase power absorbed by the load

$($b$)$ Find the total apparent power supplied by the sources