Final answer:
Mary and Louise have a percentage lease, commonly used in malls, where rent includes a portion of the business income.
Step-by-step explanation:
Mary and Louise's lease where a portion of the business income is to be paid in addition to the periodic rent is known as a percentage lease. Given their location in a regional mall, this type of lease is advantageous for both the landlord and the tenants. It allows the landlord to benefit from the success of the business, as they earn more when the business does well. At the same time, it provides some risk-sharing, as Mary and Louise will pay less in slower business periods when their income is lower.