Maths Assignment 2 (Application of The Derivative)

Assignment 2 (Application of The Derivative) 
After an aggressive marketing campaign in the local community, Poe's TV Sales & Repair Co. 
discovered that their cost can now be modeled by the equation: 
C(n) = 25n + 150n + 21500, 
where n represents the number of small screen televisions produced in a particular month. 
1. How many small screen televisions must be produced in a month in order to minimize the  company's average cost? Show all steps and justify your answer. 
2. What is that minimum average cost?