Question 934741
Drawing the picture easier done on paper than through sophisticated software and posting to an image hosting service.
The formulas for the volumes are easily done here.


BRICK VOLUME:
The two bottom dimensions are each x.
Volume is {{{x*x*(x-1)}}} and necessary restriction is {{{x>1}}}.
Standard form is probably {{{(x-1)x^2}}}  but you might really want general form, {{{highlight(x^3-x^2)}}}.


PYRAMID VOLUME:
You already have the basic formula so this should be no trouble.
Volume is {{{(1/3)pi*x^2*21}}}
simplifiable to
{{{highlight(7pi*x^2)}}}.