PMP Certification Monitoring and Controlling Test 4

A real estate company is developing a four-building complex. The project management plan calls for completion of one building per year at a cost of US$\mathrm{\$}$100 million each. At the end of year three, building one was completed at a cost of US$\mathrm{\$}$100 million, building two was completed at a cost of $\mathrm{\$}$US120 million, and building three was 50 percent complete at a cost of US$\mathrm{\$}$60 million.
To meet the original project management plan, what monthly performance is needed until the end of year four?