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

Max $2x_1+x_2$

$s.t.4x_1+1x_{2}400$

$,4x_1+3x_{2}600$

$,1x_1-2x_{2}300$

$,x_1,x_{2}0$

What is the shadow price of constraint $3?$