To find volume $ V $ use formula:
$$ V = l \cdot w \cdot h $$After substituting $l = 0.2\, \text{m}$, $w = 0.2\, \text{m}$ and $h = 0.075\, \text{m}$ we have:
$$ V = 0.2\, \text{m} \cdot 0.2\, \text{m} \cdot 0.075\, \text{m} $$$$ V = 0.04\, \text{m}^2 \cdot 0.075\, \text{m} $$ $$ V = 0.003\, \text{m}^3 $$