Define the concept of equilibrium in the simple expenditure model we developed in class. Now, explain what signal in spending will tell us that the economy is not in equilibrium? Lastly, assume that we find that actual Y is greater than equilibrium Y, Y_e thus actual current Y>Y_e. Explain the reaction by firms to this situation and what you expect to happen to the actual level of Y because of this corporate reaction. Show the graph of the initial situation and the resulting change in Y due to the corporate reaction.