Q$2.$ Write the GAMS code for the mathematical model given below. $(25$ Pts$)$

$mamize{\displaystyle \underset{j=1}{\overset{n}{}}}{p}_j{x}_j$

subject $to{\displaystyle \underset{j=1}{\overset{n}{}}}{w}_j{x}_{j}c,$

$x_{j}in\{0,1\},j=1,$dots,$n.$

$n$ : number of items

$W_j$ : weight of item $j$

$p_j$: profit of item $j$

$c$ : capacity of the knapsack

Capacitiy of Knapsack $=20$