[三级固定收益] General Bonds Corp. (GBC) has a pension liability of $100M. The duration of this liability is 15 years.On the asset side of its balance-sheet GBC has a 100% bond portfolio that consists of two bonds: a Treasury bond with duration 2 and a second Treasury bond with duration 20.If GBC’s pension board wants to insulate (immunize) the pension fund from day-to-day fluctuations of the interest rate how much should it invest in the 2-year Treasury and the 20-year Treasury respectively?