Solution:
Cost of apartment(Ben + Housemates) = $ 563 per month
Amount paid by Ben per month = $ 215
Yes, Accommodation provided by someone for fixed amount is an essential Expense.
All the three statements regarding Ben who pays $ 215 per month are true.
a. It cannot be eliminated in a later budget, in order to save money.
b. Living expenses have a higher priority than any other type of expense.
c. The spender controls the amount of the rent by choice of apartment.