What was the change in the Net cash provided by operating activities from 2018 to 2019?
{"Net cash provided by operating activities": {"2019": 116126, "2018": 140459}, "Net cash used for capital expenditures": {"2019": -48857, "2018": -12011}, "Free cash flow": {"2019": 67269, "2018": 128448}}
net_cash_2019 = df["Net cash provided by operating activities"]["2019"]
net_cash_2018 = df["Net cash provided by operating activities"]["2018"]
answer = net_cash_2019 - net_cash_2018