Answer:Situation 1: Increase in Demand for Smartphone Cases Graph:- *Original Demand Curve (D1)*: Draw a downward-sloping demand curve labeled D1.- *New Demand Curve (D2)*: Draw a new demand curve to the right of D1, labeled D2, indicating an increase in demand.Axes:- *Vertical Axis (Price)*: Label the vertical axis as "Price" and mark the price levels.- *Horizontal Axis (Quantity Demanded)*: Label the horizontal axis as "Quantity Demanded" and mark the quantity levels.Shift:- The demand curve shifts to the right from D1 to D2, indicating an increase in demand for smartphone cases due to the decrease in price of smartphones.Situation 2: Decrease in Demand for Sugary DrinksGraph:- *Original Demand Curve (D1)*: Draw a downward-sloping demand curve labeled D1.- *New Demand Curve (D2)*: Draw a new demand curve to the left of D1, labeled D2, indicating a decrease in demand.Axes:- *Vertical Axis (Price)*: Label the vertical axis as "Price" and mark the price levels.- *Horizontal Axis (Quantity Demanded)*: Label the horizontal axis as "Quantity Demanded" and mark the quantity levels. Shift:- The demand curve shifts to the left from D1 to D2, indicating a decrease in demand for sugary drinks due to the new diet trend.