The following graph shows total production (TP) and the level of Natural Real GDP (NRGDP) for a hypothetical economy. When Real GDP is $350 billion, consumption is $300 billion, government purchases are $25 billion, and investment is $50 billion. When Real GDP is $400 billion, consumption is $325 billion, government purchases are $25 billion, and investment is $50 billion. Use the blue line (circle symbol) to plot the economy's total expenditure function within a simplified Keynesian framework.