From Problem Figure 1 to 2, the lowermost design moves to the top and the left as well as the right designs are replaced with a new design. From Problem Figures 2 to 3 the right design moves to the left position and the top as well as the bottom designs are replace with new designs.
These two steps are continued alternately in the subsequent figure.
Problem Figure 1 to 2: the two pairs of diagonally opposite designs interchange positions. Similarly, the two designs of the middle row interchange positions. Similar changes occur from Problem Figure 5 to Answer Figure.