There is 60,000,000 QSD in circulation at a 60% collateral ratio. The total value of collateral across the BUSD, BNB, BTCB pools is 40,000,000 USD. There is 40,000,000 USD worth of excess collateral available for CEC buybacks. In the three kinds of collateral, the total value of the lowest is BTCB(3,700,000 USD). Assuming that a user chooses to exchange BTCB with CEC, then after exchanging all BTCB, the user can still exchange BUSD or BNB with CEC equal to 300,000 USD.