The leases in multiple-unit commercial developments commonly permit the landlord to allocate to the tenants various common area and general costs such as property taxes, janitorial services, security services, and snow removal. These costs are usually prorated on the basis of the floor area leased to each tenant. Granny’s Chicken, Toys’n Novelties, and Pine Tree Pharmacy are the three tenants in Pine Tree Square. They lease 172 square metres, 136 square metres, and 420 square metres, respectively. How should common costs totalling $9872 for the past year be allocated?