Peter plans to set up an online business selling software applications that he develops and supports. He believes that a price of $120 for his product including the technical support would be competitive. His monthly fixed expenses amount to $840. Peter would hire some college students to provide the technical support of the application paying them for 3 hours at $15 per hour for each client. 

a). How many clients does Peter need to acquire to break even? 

b). If he wants to achieve a target profit of $500 monthly, how many clients does he need?