Jason bought a new bookcase that can hold a maximum of 80 pounds of weight. Jason has 70 hardcover books that each weigh half a pound, 30 textbooks that each weigh 2 pounds, and 3 knick-knacks that each weight 6 pounds. How many pounds over the bookcase's weight limit is this total collection of items?
Please reason step by step, and put your final answer within \boxed{}.
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