题目已知：tax rate :35%
                  the firm can issue $1000 face value ,7%semi-annual coupon debt with a 15-year maturity for a price of $1047.46
我的问题的是: how to calculate "Kd"

(some indication from answer: n=15*2=30, PMT=1000*0.07/2=35 FV=1000 PV=-1047.46,CPTI=3.25 ,multiply by 2=6.5%
请问3.25到底怎么来大？)