In the question, the total material cost is 1,010,000, and the question says that this is net of discount (which from the table in the question must be 5%). So it means that the cost of 1,010,000 must be 95% of the cost before discount.
Stopping TD means losing sales and therefore saving material, as shown in the answer. Since all materials are currently getting a discount of 5%, the answer has calculated the gross cost of the materials lost.
It means that the future gross cost of materials will now be 950,000. From the table this will mean a discount of 3% which means the actual cost in future will be 97% of 950,000 which is 921,500