4000 3500- Ay 3000- 2500 2000- lyft) 1500 1000- 500- 0- y-f(0) 02 4 6 8 10 12 14 16 Years after 1980 The blue curve shows national health expenditures in billions of dollars. The red curve shows its derivative. National health expenditures (in billions of dollars) from 1980 to 1994 are given by the function f(t) in the graph to the left. (a) How much money was being spent at the beginning of 1983? $ billion