Why did visitors say the kings of Ghana were the richest men in the world?

Gettysburg address question. what is the purpose of this address?

Define production possibility curve

According to the chart, the power to tax is a concurrent power, meaning a) it belongs to the state government. b) it is a government power that is shared. c) it is less important than the power to borrow money. eliminate d) it is more important than the regulating state trade.