If you dip the whole thing in paint and cut along the dotted lines, there will be 4 cubes with 4 unpainted sides (the ones facing inwards). Since the total area is 150cm^2, the area of one side of a cube is 37.5cm^2. Since you have the area, you don’t need length breadth and height. Remember that for cubes, the length = breadth = height. Use your calculator to square root the area (37.5cm^2) to find the length of one cube which is 6.1237cm. Now you can find the volume of one cube, by taking 6.1237*6.1237*6.1237 = 229.6=230cm^3. Now simply multiply that by 4 to get the volume of the whole block, because the block is mad or 4 identical cubes.