Not sure what I am doing wrong..

**Question:**
Terry makes and sells necklaces. He has observed over time that when the price is $ 9 each, he sells an average of 30 per day. If he increases the price, then his average sales fall by 3 per day for each dollar increase. The materials for each necklace cost $8. Express his profit P as a function of x, the number of necklaces sold.

Answer: P(x)=

**What I have:**
Profit function is revenue minus cost. Thus:

P(x)=R(x)-C(x)

And R(x)= P*Q Where P is Price and Q is quantity.

**My Formula:** No. In this formula, x represents the number of dollars price increase.
Simplify:

What am I missing?