Marie is planning to open her own sandwich bar cafe in the city. The building rent is $5,500 per month plus some other costs such as internet and hydro which has been estimated to be $700 per month. She must hire three employees and need to pay them $19.5 per hour, per employee and each employee is expected to work 160 hours per month. Based on some initial estimations, the average revenue is going to be $9 per customer and the variable cost for serving each customer is going to be 2 dollars. a) How many customers per month must she serve in order for the business to break-even? b) How many customers must her establishment serve to make a monthly profit of 9,000 dollars?