4. (Tax Benefits) January 2020, Starbucks considers moving to Delaware from Seattle to reduce its marginal tax rate from current 21% to 13%. Starbucks' debt-to-equity ratio equals 0.5 and its current debt cost of capital is 6%. (a) Compute by how much this would change WACC. (b) Suppose Starbucks abandons the idea of relocation and instead decides to call $5 billion of permanent debt and replace it with convertible bonds of the same value. If the economy is strong in April, then convertible bonds convert to equity this year. If the economy in April is weak, then they remain on the balance sheet as permanent debt. Both states of the economy are equally likely. By how many would this restructuring change the present value of tax shield