a) Consider that a number in scientific notation must be written by taking into account that the absolute value of the coefficient is a number greater than 0 and lower than 10. Furthremore, the base should be 10 and the exponent must be a noz-zero integer.
Then, for the given amounts, you have:
GDP = $14.864 trillion
1 trillion is 1,000,000,000,000 or 10^12
GDP = $14.864*10^12 = $1.4864*10*10^12
GDP = $1.4864*10^13 (GDP in scientific notation)
Population = 375.6 million
1 million is 1,000,000 or 10^6
Population = 375.6*10^6 = 3.756*10^2*10^6
Population = 3.756*10^8 (Population is scientific notation)
b) By using the rules for the operations of exponents, you obtain:

Hence, the GDP per capita is approximately 3.9*10^4