Need help with this. Verify answers with second derivative test

Economics A concession stand sells drinks at an event. When the drinks are sold for $1.50 each, the stand sells approximately 3,000 drinks. When the price is increased to $1.75, the stand only sells about 2,500. (Assume the price equation is linear; i.e. p = mx +b.) It costs the owners $0.40 to make each drink and $1,000 per event to rent the space. (a) Find the price, cost, revenue, and profit functions. b How many cups of lemonade must the stand sell to maximize profit? [1] (c) What is the maximum profit? [0.2] (d) How much should they sell each cup for in order to maximize profit? [0.2]