The Missing One Rupee

one rupee puzzle
Three friends who stay in lodge sent Room boy to buy Banana. They gave him 6 rupees each. He went to the Shop Banana were not so good, Since the Bananas were not so good, the shop-keeper gave back 5 rupees. The Room boy returned and gave each lodger 1 rupee and kept the balance of 2 with him. Each lodger thus paid only Rs 5/- for the Bananas but 5x3=15+2=17.

Who took the missing one rupee..??

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