Replace each word with three synonyms where possible. For "Save", options could be Cut. For "money", funds. "by" becomes via. "downloading" fetching. "PDF version" remains as is because it's a specific term. "instead" instead. "purchasing" buying. "physical copy" printed material.
Now, processing each line step by step, making sure that each word is replaced appropriately. Let's start with the first sentence: Computer Graphics With Opengl 4th Edition Pdf Download
Moving on to the Alternative Resources section: Replace each word with three synonyms where possible
"Check online repositories: Search for the book on online repositories like Google Books, Amazon, or university libraries." options could be Cut. For "money"