The answer is: 486 If the height of the original cuboid is x, then its length and width are both (x+3). Get the equation: 3(x+3)(x+3)=243, so x=6 and x+3=9. That is, the length and width of the original cuboid are 9, and the height position is 6. So the volume x(x+3)(x+3)=486. I hope it can be adopted!