Please help me with this problem

A deli sells 720 sandwiches per day at a price of $6 each. (A) A market survey shows that for every $0.10 reduction in the price, 20 more sandwiches will be sold. How much should the deli charge in order to maximize revenue? The deli should charge $ 4.80 for a sandwich to maximize revenue. (Round to the nearest cent as needed.) (B) A different market survey shows that for every $0.20 reduction in the original $6 price, 5 more sandwiches will be sold. Now how much should the deli charge in order to maximize revenue? Now the deli should charge $ for a sandwich to maximize revenue. (Round to the nearest cent as needed.)