$4.(20$ points$)$ A steam power plant operates on a Rankine cycle with the following conditions:

$($a$)(5$ points$)$ Steam enters the turbine at $4$ MPa and $\backslash (400^\{\backslash$circ$\}\backslash$mathrm$\{$C$\}\backslash )$

$($b$)(5$ points$)$ The condenser pressure $\backslash (\{\}^\{$I$\}\backslash )$ is $10$ kPa

$($c$)(5$ points$)$ The pump work is $\backslash (2\mathrm{.}5\backslash$mathrm$\{$~kJ$\}/\backslash$mathrm$\{$kg$\}\backslash )$

$($d$)(5$ points$)$ Calculate the cycle efficiency if the turbine isentropic efficiency is $\backslash (85\backslash \%\backslash )$