A multinational is studying the possibility of buying coffee machines and installing them in the meeting rooms of its offices. In addition to helping to keep workers' attention, the machines could generate economic benefits for the company, whose cost of capital is 7%. If each machine costs 20,000, it has a useful life of 6 years, annual maintenance costs of 500 and each coffee is sold at a price of 0.75, with the unit cost of milk, sugar, teaspoon, glass and coffee. from 0.30. Determine how many coffees would need to be sold at least each year for the investment to make sense.