Read module $1$ on how to solve linear equation using Matlab.

Use Matlab to solve the following equations:

$0\mathrm{.}5*($x$1+$ x$2)+1\mathrm{.}5*($x$1+$ x$3)+3\mathrm{.}5*($x$2-$ x$3)-4*$x$4=2*4$

$-($x$1+$ x$2)-2*($x$2+$ x$3)+3*($x$3+$ x$4)+2*$x$3=3$

$2*($x$1+$ x$2+$ x$4)+4*($x$2+$ x$3)-9*($x$3+$ x$4)=2$

$-($x$1+$ x$2)-2*($x$2+$ x$3)+7*$x$3=2$

enter the value of x$4$ only.