The volume of a rectangular prism is the product of the three dimensions.
The width and length give the base area, which is 90.
So, if we multiply the base area and the height, we get the volume:
[tex]w\cdot l\cdot h = V \implies h = \dfrac{V}{w\cdot l}[/tex]
We know that V=1080 and w*l (i.e. the base area) is 90. So, we have
[tex]h=\drac{1080}{90}=12[/tex]
