Sarah has a collection of 60 marbles. She decides to give away some of her marbles to her friends. She gives 1/5 of her marbles to her friend John, 1/4 of what remains to her friend Amy, and 1/2 of what is left after that to her friend Mike. How many marbles does Sarah have left after giving the marbles to her friends? Let's think step by step and output the final answer within \boxed{}.
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