Four Pyramid Puzzles

Here are four puzzles and a key that shows the solution. The key is a four sided pyramid made of cubes. The base contains 25 sub cubes, 5x5, the second level 9 sub cubes, 3x3, and the top a single cube. The four puzzles all assemble to make the pyramid. One puzzle is composed of four pieces, a second of five pieces, a third of six pieces, and the fourth contains seven pieces.