Buy a used, previous edition. The 15th edition is chemically similar to the 18th edition. Linear Programming hasn't changed since 1947. You can buy a used copy for as little as ₹150–₹300 on platforms like or OLX (India) or AbeBooks (International).
You can also try searching for the book on online libraries and digital repositories. Operations Research By Kanti Swarup Free Pdf
Spend the ₹600–₹800. It is the cost of one pizza delivery. In return, you get a clean, searchable, high-resolution PDF (if you buy the official e-book) that will last your entire career. Operations Research is about optimal solutions. The optimal solution to "getting the book" is buying it legally—your future self, and the authors, will thank you. Buy a used, previous edition