How to calculate Cost of Debt?? understand, somebody, solution, example, totally

lxwarr30

Page:63 (CFA book vol 4 , example 11) -> Bayern Chemicals' cost to debt has an estimated spread of 225 basis points over the 10 year bund ( i guess its bond)!

and solution shows:
The before-tax cost of debt of Bayern Chemicals (rd)is 6.75 %

rd=4.5% + 2.25% = 6.75

I am totally confused how they got this value, can somebody help me understand this calculation of Cost of Debt?

Given:risk free long term bond rate=4.5%

http://www.finomist.com