Why does the price of airline tickets rise during the summer months? The demand for air travel shifts to the left, increasing price and quantity supplied. The quantity of air travel demanded decreases, increasing price and quantity supplied. The demand for air travel shifts to the right, increasing price and quantity supplied. The quantity of air travel demanded increases, increasing price and quantity supplied. b. Demonstrate your answer to part a graphically. Instructions: Draw a parallel shift in either the demand or supply curve by grabbing, dragging, and then dropping the curve to the new position.