A square piece of paper has a dot in its top right corner and is lying on a table. The square is folded along its diagonal, then rotated clockwise about its centre, and then finally unfolded, as shown.
The resulting figure is
Problem 80
Official solution
We draw an unshaded dot to represent the location of the dot when it is on the other side of the sheet of paper being shown. Therefore, the dot moves as follows:
[[IMAGE0]]
It is worth noting that folding and unfolding the paper have no net effect on the figure. Thus, the resulting figure can be determined by rotating the original figure by clockwise.