If the total volume of the box is 24 cm³ and the volume of each cube is 1 cm³then that means that 24 total cubes can fit perfectly inside the box. Since there can only be two layers of cubes then we simply need to divide the total amount of cubes that will fit in the box by 2 to find the number of cubes in each layer...
24 / 2 = 12 cubes
Finally, we can see that each layer within the box will contain 12 cubes
Using the rectangular route Mike rides 12 miles. If he rides diagonally the distance is √2²+10²=√4+100=√104. The difference between the two routes is 12-√104=1.80 miles approximately.