The phrase "me las vas a pagar" translates colloquially to "you will pay me for this" (a threat of revenge), which in this context is likely the who created a series of challenging algebra problems. Mary Rojas might be a fictional name or an alias used by a tutor.
You can read it legally on Booknet , where Mary Rojas publishes most of her "Enferma" and "Obsesión" series. me las vas a pagar mary rojas pdf %C3%A1lgebra
If you are looking for (textbooks, exercises, solutions) by an author named Mary Rojas, there is no widely known math author by that name. The phrase "me las vas a pagar" translates