Total concrete volume:
\[ \text{total concrete volume} = \text{length} \times \text{width} \times \text{depth} \]
Total gravel volume:
\[ \text{total gravel volume} = \text{length} \times \text{width} \times \text{gravel depth} \]
Total rebars length:
\[ \text{total rebars length} = (\frac{\text{length} - 2 \times \text{edge rebar spacing}}{\text{rebar spacing}}) \times (\text{width} - 2 \times \text{edge rebar spacing}) \times 2 \]
Rebar pieces:
\[ \text{rebar pieces} = \frac{\text{total rebars length}}{\text{single rebar length}} \]
Total forms length:
\[ \text{total forms length} = 2 \times (\text{length} + \text{width}) \]
Total costs:
\[ \text{total cost} = \text{total concrete volume} \times \text{concrete price} + \text{total gravel volume} \times \text{gravel price} + \text{total rebars length} \times \text{rebar price} + \text{total forms length} \times \text{form price} \]
