If 100 cats killed 100 mice in 100 days, you can say that each cat killed one mouse the day after the last cat. So, if four cats killed four mice, and we're going of off the same basis that each cat killed one mouse the day after the last cat, then the answer would be 4.
H^3+3h^2x+3hx^2+x^3 should be the answer
The equation for the line of reflection is x = 2.
If you drew a vertical line crossing the x-axis on x = 2, the drawing will be the same on the left and right side, as if one side was drawn then exactly copied on the other side but flipped.
The figure is symmetrical, and x = 2 is the line of symmetry.
Hope this helps!