Why did the Egyptian pharohs build stronger fortresses between the 2nd and 3rd cataracts of the Nile after the first around 2100BCE.

Using only this chart, which step would you take first to compare the standard of living in these countries? add the gdp numbers for the countries to get a total. divide each gdp number by its country's population. subtract each population number from its country's gdp. multiply the population number by the gdp for each country.