What is the difference between the total constructions (constructed, demolished and redeveloped) in city Q and city T?

Total constructions in City Q = constructed building + demolished building + redeveloped building
Total constructions in City Q = 100 + 175 + 275 = 550
Total constructions in City T = constructed building + demolished building + redeveloped building
Total constructions in City T = 175 + 250 + 300 = 725
Their difference = 725 - 550 = 175