Find the volume v of the described solid s. a frustum of a pyramid with square base of side b, square top of side a, and height h

Use the general formula:

Volume = Height * (area of top+4*area at mid height+area at bottom) / 6

Example for a cube of side s:

Vcu=s (s^2+4s^2+s^2) / 6=s^3

Example for a cone of radius r

Vco=h (0+4*pi r^2/4+pi r^2) / 6=pi r^2 h/3

Example for a sphere or radius r:

Vsph=2r * (0+4pi r^2 + 0) / 6 = 4pi r^2 / 3

So for a square frustrum with end sides a & b, height h:

Vf=h * (a^2+4 ((a+b) / 2) ^2+b^2) / 6 = (a^2 + (a+b) ^2+b^2) h/6

or simply

Vf = (a^2 + (a+b) ^2+b^2) h/6