Amal purchases some pens at $₹ \; 8$ each. To sell these, he hires an employee at a fixed wage. He sells $100$ of these pens at $₹ \; 12$ each. If the remaining pens are sold at $₹ \; 11$ each, then he makes a net profit of $₹ \; 300,$ while he makes a net loss of $₹ \; 300$ if the remaining pens are sold at $₹ \; 9$ each. The wage of the employee, in $\text{INR},$ is