Amount of gravel:
\[ \text{amount of gravel} = \text{length} \times \text{width} \times \text{depth} \]
Gravel weight:
\[ \text{gravel weight} = \text{amount of gravel} \times \text{crushed stone weight} \]
Total cost:
\[ \text{total costs} = \text{amount of gravel} \times \text{price (per cubic meter or cubic yard)} \]
