A mobile phone manufacturer charges $200/phone and sells 20000 phones each month at this price. For every increase of $20 in price, the number of phones sold goes down by 1000. #SAT #ACT
1. How many phone will be sold/month if the price is set to $300?
2. What will be the monthly revenue from the sale of phones at $300/phone?
3. What will be the monthly revenue if each phone is sold at $X (200 =< X =< 600)?