Julia is packing snacks for her hiking trip. She packs 3 types of snacks: granola bars, fruit snacks, and trail mix. She packs 5 granola bars, 8 fruit snacks, and twice as many trail mix packs as the total number of granola bars and fruit snacks. How many snack packs did Julia pack in total? Let's think step by step and output the final answer within \boxed{}.
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