students like Mozart, but neither Beethoven nor Haydn

In a certain company 80 of the employees are men. What is the total number of employees if 5 out of every 8 employees are men?

A merchant surveyed 540 people to determine the way they learned about an upcoming sale. The survey showed that 210 learned about the sale from the​ radio, 250 from​ television, 200 from the​ newspaper, 100 from radio and​ television, 50 from radio and​ newspapers, 90 from television and​ newspapers, and 30 from all three sources. How many people learned of the sale from newspapers or​ radio, but not​ both?

A farmer knows that of every 50 eggs his chickens lay, only 45 will be marketable. If his chickens lay 1900 eggs in a week, how many of them will be marketable?