If a firm issues $200 debt forever at an annual interest rate of 6% (cost of debt and coupon rate), what is the present value of interest tax shields? Assume the firm pays interest at the end of each year, debt is re-issued at the same rate when due, and the interest tax shields fall into the same risk class as the firm's debt. The corporate tax rate is 23%, the firm equity beta is 1.3, and the risk-free interest rate is 3%