Question 375422
Janet, the best I can do with your description is the following:
It looks like you have a three-dimensional solid with one face in the shape of a trapezoid.
The trapezoid has dimensions of:
Base = 25ft.
Left side (perpedicular to the base) = 9ft.
Right side (perpendicular to the base) = 16ft.
Now extend this trapezoid shape 18ft. (We'll call this the "depth" of the solid) away from, but perpendicular to, the 25ft. base.
To find the volume of this solid, first find the area of the trapezoid.
{{{A = (1/2)(b[1]+b[2])*h}}} Substitute {{{b[1] = 9}}}, {{{b[2] = 16}}}, and {{{h = 25}}}
{{{A = (1/2)(9+16)(25)}}}
{{{A = (1/2)(25)*(25)}}}
{{{A = (1/2)(625)}}}
{{{A = 312.5}}}sq.ft. 
Now find the volume by multiplying the area of the trapezoid (312.5sq.ft.) by the "depth" (18ft.).
{{{V = (312.5)*(18)}}}
{{{highlight(V = 5625)}}}cu.ft.
I hope I have interpreted your description correctly.