
you're given all those values, h,k and r, so just plug them in
Add the following polynomials:
All polynomials are already ordered according to their degree (exponent), and therefore you can just add straight down in columns.
For x3: 2 + 1 - 3 = 0
For x2: -4 + 6 + 2 = 4
For x: 6 - 8 -4 = -6
Constants: -3 + 12 - 7 = 2
The answer is:
4x^2 - 6x + 2
In order to compute the markup, compute the percentage like this:

The markup is then $12,32.
The selling price is the sum of the cost and the markup:
Easy, it is 1. I hope that helps =D