Solve the following FOUR variable linear program using Excel. $($You cannot solve this problem easily with the graphical method$).$

MAXIMIZE $2x1+52+3x3+7x4$; subject to the constraints:

$x1+x2+x3+x410$

$2x1+3x2+1x3+6x417$

$x10$;$x20,x30,x40$

$x2=6\mathrm{.}5$ in the optimal solution.

$x2=4\mathrm{.}5$ in the optimal solution.

$x2=3\mathrm{.}5$ in the optimal solution.

$x2=5\mathrm{.}5$ in the optimal solution.