The width of rectangular solid is 20ft, which is 4/5 of its length. the height of it is 2/9 of the sum of the length and width. what is the volume of the rectangular solid? v = ? ft to the third power

Let L and H represent length and height, respectively.
.. 20 ft = (4/5)*L
.. L = (5/4)*(20 ft) = 25 ft . . . . . . . . multiply by the reciprocal of the coefficient of L

.. H = (2/9)*(L +20 ft)
.. = (2/9)*(25 ft +20 ft))
.. = (2/9)*(45 ft) = 10 ft

The volume is the product of length, width, and height.
.. V = (25 ft)*(20 ft)*(10 ft) = 5000 ft^3