Saba Conducts Regular Tours of His Favorite City in the World

Essay

Saba conducts regular tours of his favorite city in the world, Paris. Each semester he selects among the finest students in the university and escorts them to the City of Lights. In addition to a world-class education on conducting business in Europe, he arranges a number of cultural outings for them to help them immerse themselves in all that France has to offer. He collects an extra $100 from each student for this purpose and limits his tour group to ten lucky individuals. Some of the events (and their prices) he proposes to the students include:
Eiffel Tower visit, $40 per student, E
Paris Sewer spelunking, $20 per student, S
Half day passes to the Louvre, $60 per student, L
Bon Beret tour, $50 per student, B
So much to do and so little time!
-What would the constraints be if the Eiffel Tower visit needed to take place at the same time as the half day at the Louvre and if students taking the Paris Sewer tour had to wear the special sanitary beret available only from the Bon Beret tour?