A piston$-$cylinder setup is subjected to a load such that the pressure is

proportional to its volume, i$.$e$.P=CV.$ The piston$-$cylinder initially contains $H_{2}O$

at $90C$ and $100$kPa, but after heat is added the temperature reaches $200C.$

Find $P$ and $x$ if the water is in the liquid$-$vapor two$-$phase region.