The reason why has to do with law, marriage and a family that disagreed with their patriarch's evolving views on slavery. Like nearly all wealthy landowners in Virginia, George Washington owned enslaved people who worked his land. He received the first enslaved workers of his own when his father died in 1743.
The trans Atlantic slave trade was the largest movement of people in history.
Answer: between 10 and 15 million Africans
Four of those inventions were, The hot air balloon, the light bulb, mayonnaise and the piano. (: Hope this helps!