Suppose customers in a hardware store are willing to buy n(p) boxes of nails at p dollars per box, as given by the following function.
n(p) = 80 - 4p^2 ; 1 < = p < = 4.
find the average rate of change in the number of boxes of nails that customers are willing to buy (demand) for a change in price from $2 to $3.
the average rate of change of demand for a change in price from $2 to $3 is boxes per dollar.
(type an integer or a decimal.)
i know the answer (-20) but i am not sure how to get it. can you ?

Mrs. julien’s and mrs. castillejo’s classes are selling cookie dough for a school fundraiser. customers can buy packages of macadamia nut chip cookie dough and packages of triple chocolate cookie dough. mrs. julien’s class sold 25 packages of macadamia nut chip cookie dough and 30 packages of triple chocolate cookie dough for a total of $221.25. mrs. castillejo’s class sold 5 packages of macadamia nut chip cookie dough and 45 packages of triple chocolate cookie dough for a total of $191.25. (a) write the system of equations that model the problem. be sure to explain which equation represents which situation. (b) find the cost of each type of cookie. show your work. (c) explain which method you used to solve the system and why you chose that method.