I believe it’s A because if you notice the rate of population grow was in the 20,000s for the US in the 1840s, while NC was hitting 600 free people at that time.
We start out with x/3+6=-6. Subtract 6 from both sides, and you get x/3=-12. Multiply the equation by three and you get x=-36. x=-36 should be your final answer.
