3 Now you try: 1. Write down demand and supply equations for wireless phones; include two exogenous variables in each equation. 2.Draw a supply-demand graph for wireless phones. 3. Use your graph to show how a change in one of your exogenous variables affects the model's endogenous variables. CHAPTER 1 The Science of Macroeconomics slide 23 CHAPTER 1 The Science of Macroeconomics slide 23 Now you try: 1. Write down demand and supply equations for wireless phones; include two exogenous variables in each equation. 2. Draw a supply-demand graph for wireless phones. 3. Use your graph to show how a change in one of your exogenous variables affects the model’s endogenous variables. 3