To multiply binomials, use the FOIL method. FOIL stands for First, Outside, Inside, Last and refers to the position of each term in the parentheses.

The formula for circumference is circle diameter x π:

c = πd
c = 5π

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.

(4a)(7ab) - (5a²)(8b)
(4 x 7)(a x a x b) - (5 x 8)(a² x b)
(28)(a¹⁺¹ x b) - (40)(a²b)
28a²b - 40a²b
-12a²b

To factor a quadratic expression, apply the FOIL method (First, Outside, Inside, Last) in reverse. First, find the two Last terms that will multiply to produce 24 as well and sum (Inside, Outside) to equal 10. For this problem, those two numbers are 4 and 6. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² + 10y + 24
y² + (4 + 6)y + (4 x 6)
(y + 4)(y + 6)

The surface area of a cube is (2 x length x width) + (2 x width x height) + (2 x length x height):

sa = 2lw + 2wh + 2lh
sa = (2 x 8 x 8) + (2 x 8 x 6) + (2 x 8 x 6)
sa = (128) + (96) + (96)
sa = 320