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That is the correct answer and you are the first to provide it @javiervasquez. Congrats! It's actually more of a visual puzzle rather than a math one...all you have to do is invert the picture to look at it from the other perspective and you will see the stall is supposed to be #87! SBD is on the way...

Thank you very much @brainteasers. I hope to play again with this kind of puzzles from you!!