Explanation:
it is a box or prism.
the volume is simply
length × width × height
in our case
8m × 6m × 5m = 240 m³
doubled dimensions means
16m × 12m × 10m = 1920 m³
the difference is
1920 - 240 = 1680 m³
we could have gotten the new volume also based on the original volume :
2×8m × 2×6m × 2×5m = 8m×6m×5m × 2×2×2 =
= the original volume (240 m³) × 8 = 1920 m³