At a mexican fast-food chain, a customer a) decides what type of food s/he wants (e. g., burrito, salad, or tacos), b) decides what fillings s/he wants (e. g., chicken, fish, or vegetable), c) decides what toppings s/he wants (e. g., lettuce, guacamole, or cheese), and d) pays for the order that may or may not include a drink. one employee works at each of the steps a) through c), and two employees take care of the payment. per customer, step a) takes 2 minutes on average, step b) takes 3 minutes on average, step c) takes 1 minute on average, and step d) takes 4 minutes on average. suppose another person is hired for step b), what is the system capacity?