6. MobiStar is a mobile services company that sells 800 phones each week when it charges $80 per phone. It sells 40 more phones per week for each
$2 decrease in price. The company's revenue is the product of the
number of phones sold and the price of each phone. What price should
the company charge to maximize its revenue?
Part A: Let d represent the number of $2 decreases in price. Letr be the
company's revenue. Write a quadratic function that reflects the
company's revenue.
Hint: The number of phones sold will be 800 + 40d since they sell 40 more
phones for every $2 decrease. The price for the phones will be 80 - 2d
since d is the number of decreases and each decrease is $2.