What was the total net book value of leased land and buildings and leased plant and machinery?
{"": {"Leased land and buildings": "\u00a3m", "Leased plants and machinery": "\u00a3m", "Leased fixtures, fittings, tools and equipment": "\u00a3m", "Total right-of-use assets": "\u00a3m"}, "Cost: -- Transition adjustment at 1st January 2019": {"Leased land and buildings": 27.2, "Leased plants and machinery": 7.0, "Leased fixtures, fittings, tools and equipment": 1.9, "Total right-of-use assets": 36.1}, "Cost: -- Reclassification from long-term prepayments": {"Leased land and buildings": 5.1, "Leased plants and machinery": "\u2013", "Leased fixtures, fittings, tools and equipment": "\u2013", "Total right-of-use assets": 5.1}, "Cost: -- Additions": {"Leased land and buildings": 7.2, "Leased plants and machinery": 4.2, "Leased fixtures, fittings, tools and equipment": 0.3, "Total right-of-use assets": 11.7}, "Cost: -- Acquisitions": {"Leased land and buildings": 0.8, "Leased plants and machinery": 0.3, "Leased fixtures, fittings, tools and equipment": "\u2013", "Total right-of-use assets": 1.1}, "Cost: -- Disposals": {"Leased land and buildings": -0.2, "Leased plants and machinery": -0.1, "Leased fixtures, fittings, tools and equipment": "\u2013", "Total right-of-use assets": -0.3}, "Cost: -- Exchange adjustments": {"Leased land and buildings": -1.5, "Leased plants and machinery": -0.4, "Leased fixtures, fittings, tools and equipment": -0.1, "Total right-of-use assets": -2.0}, "Cost: -- At 31st December 2019": {"Leased land and buildings": 38.6, "Leased plants and machinery": 11.0, "Leased fixtures, fittings, tools and equipment": 2.1, "Total right-of-use assets": 51.7}, "Depreciation: -- Charged in the year": {"Leased land and buildings": 7.0, "Leased plants and machinery": 3.7, "Leased fixtures, fittings, tools and equipment": 0.6, "Total right-of-use assets": 11.3}, "Depreciation: -- Disposals": {"Leased land and buildings": -0.1, "Leased plants and machinery": "\u2013", "Leased fixtures, fittings, tools and equipment": "\u2013", "Total right-of-use assets": -0.1}, "Depreciation: -- Exchange adjustments": {"Leased land and buildings": -0.2, "Leased plants and machinery": -0.1, "Leased fixtures, fittings, tools and equipment": "\u2013", "Total right-of-use assets": -0.3}, "Depreciation: -- At 31st December 2019": {"Leased land and buildings": 6.7, "Leased plants and machinery": 3.6, "Leased fixtures, fittings, tools and equipment": 0.6, "Total right-of-use assets": 10.9}, "Net book value: -- At 31st December 2019": {"Leased land and buildings": 31.9, "Leased plants and machinery": 7.4, "Leased fixtures, fittings, tools and equipment": 1.5, "Total right-of-use assets": 40.8}}
net_book_value_land_buildings = df["Net book value: -- At 31st December 2019"]["Leased land and buildings"]
net_book_value_plants_machinery = df["Net book value: -- At 31st December 2019"]["Leased plants and machinery"]
answer = net_book_value_land_buildings + net_book_value_plants_machinery