$3\mathrm{.}90$ Superheated refrigerant $R-134a$ at $20C$ and

$100$ kPa is cooled in a piston$/$cylinder arrange$-$

ment at constant temperature to a final two$-$phase

state with quality of $50\%.$ The refrigerant mass is

$3$ kg $,$ and during this process $357$ kJ of heat is

removed. Find the initial and final volumes and the

necessary work.