A school's weekly cafeteria sales are represented in a bar graph. The graph shows that on Monday, 200 sandwiches were sold, on Tuesday, 150 sandwiches were sold, on Wednesday, 250 sandwiches were sold, on Thursday, 100 sandwiches were sold, and on Friday, 300 sandwiches were sold. How many more sandwiches were sold on Friday than the average number of sandwiches sold per day from Monday to Thursday? Let's think step by step and output the final answer within \boxed{}.
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