Please provide a detailed step by step solution. I am lost and missing core concepts.

A company is decreasing production of math-brain protein bars at a rate of 400 cases per day. All cases produced can be sold. The daily demand function is given by _i where x is the number of cases produced and sold, and p is in dollars. If the daily production is 300 cases, then revenue is 0 increasing 0 decreasing at a rate of|:] dollars per day