math
posted by beth .
Terry makes and sells necklaces. He has observed over time that when the price is $12 each, he sells an average of 20 per day. If he increases the price, then his average sales fall by 2 per day for each dollar increase. The materials for each necklace cost $7. Express his profit P as a function of x, the number of necklaces sold.
that would make p(x)= ?
THANK YOU!

at price z, demand
x = 202(z12)
or, price z = 22  x/2
p(x) = revenuecost
= x(22  x/2)  7x
= 15x  1/2 x^2