Edmund runs a gift wrapping shop where he uses 18 inches of gift wrapper per gift box. He buys a roll of gift wrapper that increases in length by a factor of 2 every week. If he starts with a roll of 90 inches and wraps an equal number of gift boxes each day, how many gift boxes will he be able to wrap in the third week? Let's think step by step and output the final answer within \boxed{}.
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