Anew shop wants to sell muffins, the sell price is 2.5 dollars per unit. the cost for production is 1 dollar per unit. at the first day, they made 2000 units, however, they overestimated the demand, so they had to resell the rest to other shops 0. 5 per muffin, under this condition, the first day’s profit was at breakeven point. the second day, the boss changed the number of productions based on the first day’s sale. and plan to set "buy one get a free one" strategy to attract customers. since the muffins’ good taste, a lot of customers came back to buy muffins again and brought their friends asnew customers, so 100 of the customers did not get the muffins, per muffins loss is 2 dollars. the second day’s profit is 400 dollars. how many changes on the two day’ production? g