We need to know the dimension of the paving stone.
For example, the paving stone is shaped like a rectangular prism with the following dimension.
Length = 10 inches
Width = 3 inches
Height = 2 inches
Volume of a rectangular prism = Length Width Height
V = 10 in 3 in 2 in
V = 60 in³
60 in³ / 4 in³ = 15
cost of paving stone = 2.50 + .18(15) = 2.50 + 2.7 = 5.20 per paving stone.
