The volume of a cuboid is given in terms of length, width, and height by ...
... V = LWH
Filling in the given numbers, we can solve for the height.
... 8100 in³ = (30 in)(15 in)H
Dividing by the coefficient of H, we have ...
... (8100 in³)/(450 in²) = H = 18 in
The chest will be 18 inches tall.