What is the average total NLA of Sunshine Coast and Gold Coast?
{"Brisbane": {"NUMBER OF CENTRES": 5, "TOTAL NLA": 25000}, "Gold Coast": {"NUMBER OF CENTRES": 4, "TOTAL NLA": 6500}, "Sunshine Coast": {"NUMBER OF CENTRES": 1, "TOTAL NLA": 6500}, "Central Coast (NSW)": {"NUMBER OF CENTRES": 6, "TOTAL NLA": 20600}, "Wollongong": {"NUMBER OF CENTRES": 3, "TOTAL NLA": 12700}, "Melbourne": {"NUMBER OF CENTRES": 2, "TOTAL NLA": 8600}, "Adelaide": {"NUMBER OF CENTRES": 3, "TOTAL NLA": 15500}, "Perth": {"NUMBER OF CENTRES": 2, "TOTAL NLA": 10800}, "Auckland (NZ)": {"NUMBER OF CENTRES": 3, "TOTAL NLA": 27000}, "Hamilton (NZ)": {"NUMBER OF CENTRES": 4, "TOTAL NLA": 21600}, "Rotorua (NZ)": {"NUMBER OF CENTRES": 1, "TOTAL NLA": 5000}, "Tauranga (NZ)": {"NUMBER OF CENTRES": 1, "TOTAL NLA": 3200}, "Total Acquisitions": {"NUMBER OF CENTRES": 35, "TOTAL NLA": 163000}}
gold_coast_total_nla = df["Gold Coast"]["TOTAL NLA"]
sunshine_coast_total_nla = df["Sunshine Coast"]["TOTAL NLA"]
number_of_centres = df["Melbourne"]["NUMBER OF CENTRES"]
answer = ( gold_coast_total_nla + sunshine_coast_total_nla ) / number_of_centres