What is the increase / (decrease) in the cash from 2018 to 2019?
{"($ in millions) -- At December 31:": {"2019": 2019, "2018": 2018}, "($ in millions) -- Cash and cash equivalents": {"2019": 1697, "2018": 1833}, "($ in millions) -- Net investment in sales-type and direct financing leases (1)": {"2019": 6224, "2018": 6924}, "($ in millions) -- Equipment under operating leases external clients (2)": {"2019": 238, "2018": 444}, "($ in millions) -- Client loans": {"2019": 12884, "2018": 12802}, "($ in millions) -- Total client financing assets": {"2019": 19346, "2018": 20170}, "($ in millions) -- Commercial financing receivables": {"2019": 3820, "2018": 11838}, "($ in millions) -- Intercompany financing receivables (3) (4)": {"2019": 3870, "2018": 4873}, "($ in millions) -- Total assets": {"2019": 29568, "2018": 41320}, "($ in millions) -- Debt": {"2019": 24727, "2018": 31227}, "($ in millions) -- Total equity": {"2019": 2749, "2018": 3470}}
cash_2019 = df["($ in millions) -- Cash and cash equivalents"]["2019"]
cash_2018 = df["($ in millions) -- Cash and cash equivalents"]["2018"]
answer = cash_2019 - cash_2018