4. Mia makes necklaces to sell at an art fair. She
can set the price however she wants, but the
number of items she can sell decreases as the
price increases. In particular, if the price is
given by P(x) = x, in dollars, then the quantity
she sells is Q(x) = 30 - 5x. Her total revenue is
the product of the price and the quantity she
sells, and her profit is revenue minus cost. If it
costs Mia $2 to make each item that she sells,
which function gives Mia's total profit?
P(x) - 20(x) = 11x - 60
® P(Q(x)) - 2 = -5x + 28
© P(x)Q(x) – 2Q(x) = -5x2 + 40x - 60
D Q(x) - 2P(x)Q(x) = 10x2 - 65x + 30