In the following linear programming problem, how much would you be willing to pay for an additional $4$ units of Resource W$?($Note: This problem requires Solver.$)$

Maximize $P=3x+15y$

Subject $to$:

$,2x+4y12($ Resource $W)$

$,5x+2y10(ResourceZ)$

$,x,y0$

$0$

$11\mathrm{.}25$

$15$

$18\mathrm{.}75$