Suppose the economy of a country is experiencing inflation, and the Central Bank wants to decrease the money supply to control inflation. The current money supply is $4 trillion, and the required reserve ratio is 10%. The Central Bank decides to sell government securities worth $500 billion to reduce the money supply. Calculate the change in the money supply after the sale of government securities, assuming that the currency-to-deposit ratio is 0.2 and banks do not hold excess reserves. Show all your calculations.