Kingtim Co. (paper Dec 2020 )

Hello sir,
This may be a silly doubt.
the bond is issued at premium, so I think the first year interest expense after tax maybe
Additional finance cost (BV*YTM*0.75)=(60m/100*109.9*6.43%*0.75) =(3179)

But answer is Additional finance cost ($60m x 7·5% x 0·75) (3,375 )
Can I assume that the answer simplifies the process, it seems to think that this bond is issue at par value.

Many thanks.