After a certain medicine is injected, its concentration in the bloodstream changes exponentially over time. The graph describes the medicine's concentration (in milligrams per liter) over time (in hours).
A decreasing exponential function passes through the point (0, 100) and the point (1,70).
A decreasing exponential function passes through the point (0, 100) and the point (1,70).
What was the concentration of the medicine when it was injected?
milligrams per liter