Answer:
x^2 - 14x + 49
Step-by-step explanation:
(x - 7)(x - 7) = x^2 -7x - 7x + (7)(7)
Let N be the number of items sold and p the price.
Since the variation is inverse, then the relation between N and p is:

For N=20000 and p = $9.5, we get the formula:

If p = 8.75, then the number of items sold can be computed using the formula:
5x^2+24x-5 factored is: (5x - 1)(x + 5)
Well 19 would be 399 and for 20. the discount is 12.87 and the price of it after the discount is 26.13