The optimal solution of this linear programming problem is at the intersection of constraints of constraints $1($c$1)$ and $2($c$2).$

Max $2$x$1+$ x$2$

s$.$t$.4$x$1+1$x$2<=400$

$4$x$1+3$x$2<=600$

x$1,$x$2>=0$

Compute the dual prices for the three constraints