18. This graph shows the profit, P dollars, on a company's sale of n baseball caps. 2400 1600- Profit (S) 800- 0- 800- P= f(n) n 200 400 600 Number sold a) How many baseball caps have to be sold before the company begins to make a profit? b) What is the profit on the sale of each baseball cap? c) How many caps have to be sold to make each profit? i) $600 ii) $1200 d) In part c, when the profit doubles why does the number of baseballs caps sold not double?