Use Solver to obtain the optimal solution to the following LP:

Maximize P $=2$x$1+4$x$2+$ x$3-$ x$4$

subject to $2$x$1+$ x$2+2$ x$3+3$ x$412$

$2$x$2+$ x$3+2$ x$420$

$2$ x$1+$ x$2+4$ x$316$

a$)$ Which constraint$($s$)$ have excess capacity in the optimal solution? How many units of

each can be sold off without impacting the optimal solution?

b$)$ If one could increase the right$-$hand side of just one of the constraints by one unit, which

is the best one to increase?