now, the first one, on the far-left.... can't see the height.. but I gather you do, now as far as its Base area, well, the bottom is just a 12x12 square, so the area of its base is just 12*12
now, the middle pyramid, has a height of 6, the base is also a square, 8x8, so the Base area is just 8*8
now the last one on the far-right
has a height of 8, the Base is a Hexagon, with sides of 6