What are the values of x$,$ y$,$ and z after the following code executes $?$ int x $=3$ ; int y $=$ x int z $=$ xy; x $+$ z; x $=3$; y $=3$; z $=9$; x $=4$v $=4$; z $=12$; x $=0$; y $=3$; z $=0$; x $=4$; v $=4$; z $=9$; x $=4$; y $=3$; z $=9$