Wage Discrimination in the labor market

In your textbook in chapter 14 there is a figure 14.5 that shows wage discrimination in the labor market. What are the key assumptions made when constructing that figure? Please use the same set-up to illustrate: i) a labor market A where there is no employer discrimination (d=0) and ii) labor market B where all employers are discriminating against African American workers, but their psychic costs vary (not all employers have identical d's --- some discriminate more, some discriminate less). Note that you need to create two separate graphs.