The table in the next column lists some national accounts data for the United States in 2008
a. Calculate U.S. GDP in 2008 .
$$\begin{array}{lr}
\text { Item } & \text { Billions of dollars } \\
\hline \text { Wages } & 8,000 \\
\text { Consumption expenditure } & 10,000 \\
\text { Other factor incomes } & 3,200 \\
\text { Investment } & 2,000 \\
\text { Government expenditure } & 2,800 \\
\text { Net exports } & -700 \\
\text { Depreciation } & 1,800
\end{array}$$
b. Explain the approach (expenditure or income) you used to calculate GDP.