A store sells about 40 video game systems each month when it charges $200 per system. for each $10 increase in price, about 1 less system per month is sold. The store's revenue can be modeled by r(x)=(22+10x)(40-x), where x represents the number of price increases. How can the store maximize monthly revenue?

Afarmer has a large field that is x feet in length. he wants to fence in a rectangular section in the middle of the field , leaving a length of 100 feet of open field behind each end of the fenced rectangle.he also wants the width of the fenced-in space to be 100 feet less than its length. find the expressions to represent the length and width of the fenced section of the field