Please show working out

10.2 Woodner Lid provides a standard service. It is able to provide a maximum of 100 units of this service each week. Experience shows that at a price of 2100, no units of the ser- vice would be sold. For every 25 below this price, the business is able to sell 10 more units. For example, at a price of 295, 10 units would be sold, at $90, 20 units would be sold and so on. The business's fixed costs total $2,500 a week. Variable costs are $20 per unit over the entire range of possible output. The market is such that it is not feasible to charge different prices to different customers. Required: What is the most profitable level of output of the service