HELP Which of the following expressions illustrates the commutative property of addition?

4 + (1 + 8) = (4 + 1) + 8

-4(5) = 5(-4)

3 + (-7) = (-7) + 3

-2(6 + 8) = (-2)(6) + (-2)(8)

Evaluate 4 a for a = 5 2/3 . express your answer in simplest form.

How many real and imaginary solutions does the equation x^2-3x=-2x-7 have?

Suppose that the price p (in dollars) and the weekly sales x (in thousands of units) of a certain commodity satisfy the demand equation 4p cubedplusx squaredequals38 comma 400. determine the rate at which sales are changing at a time when xequals80, pequals20, and the price is falling at the rate of $.20 per week.