Dolorous Edd Co$.$ sells stained dragon$-$glass windows, door$-$to$-$door. Edd pays his employees $$60$ for every window sold. Edd pays $$200$ for each window and sells them for a $50\%$ mark up above the cost he pays for the stained glass. He has a fixed cost of advertising each year of $$120,000,$ but incurs no other costs.

Required:

A$.$ How many stained window units must Edd sell to break even?

B$.$ How many units must Edd sell to earn a target profit of $$250,000?$

C$.$ If budgeted sales total $5,000$ units, how much is the company's safety margin in dollars?