To multiply monomials, multiply the coefficients (the numbers that come before the variables) of each term, add the exponents of like variables, and multiply the different variables together.

(5a)(4ab) - (9a²)(8b)
(5 x 4)(a x a x b) - (9 x 8)(a² x b)
(20)(a¹⁺¹ x b) - (72)(a²b)
20a²b - 72a²b
-52a²b

A cube is a rectangular solid box with a height (h), length (l), and width (w). The volume is h x l x w and the surface area is 2lw x 2wh + 2lh.

A circle is a figure in which each point around its perimeter is an equal distance from the center. The radius of a circle is the distance between the center and any point along its perimeter. A chord is a line segment that connects any two points along its perimeter. The diameter of a circle is the length of a chord that passes through the center of the circle and equals twice the circle's radius (2r).

A trapezoid is a quadrilateral with one set of parallel sides.

The volume of a cylinder is πr²h:

v = πr²h
v = π(9² x 7)
v = 567π