I bought a book where the exercises are given in Maple worksheet format (.mw). Is there an open-source software in Linux able to interpret or to convert this specific file format ?
Maple has a built-in function for converting the code into other languages. It is called Code Generation.
You can reach a person who has Maple and ask her/him to do it for you.
I don't think such luxury is available. As a possible solution to your problem, contact some one with maple license, so that he can copy the contents of .mw file to some text editor and mail back to you.