Once Africans boarded the slave ships for the journey to the Americas, what percentage did not survive the six to eight week voyage?

According to the estimates and the historical sources that we have around one fifth of them would not survive the journey. Of course, that was due horrible conditions they were exposed on the ships.

Explanation:

Because the journey lasted sometimes even two months there were factor that led to death of many ships aboard. Firstly, those were the weather conditions, that would change during the journey. On the other side, there is also a factor of diseases and hunger that were rather frequent. People, especially men were shackled and could not even move.

b) the confederacy had to pay all union war expenses.

i would say that the politicial parties from state to state varies.