Find the length of a rectangular parallelepiped, the volume of which is 13.5 cm 3, width 4.5 cm and height 4 mm.

For a rectangular parallelepiped V = Sbase ∙ h.
Since there is a rectangle at its base, Sosn = a ∙ b, where a and b are the lengths of its sides.
Thus, V = a ∙ b ∙ h.
Hence the length will be: b = V: (a ∙ h).
Let’s determine the length of our rectangular parallelogram (its height is 4 mm = 0.4 cm):
b = 13.5: (4.5 ∙ 0.4) = 7.5 (cm).
Answer: its length is 7.5 cm.