Angles around a line add up to 180°. Angles around a point add up to 360°. When two lines intersect, adjacent angles are supplementary (they add up to 180°) and angles across from either other are vertical (they're equal).

A line on the coordinate grid can be defined by a slope-intercept equation: y = mx + b. For a given value of x, the value of y can be determined given the slope (m) and y-intercept (b) of the line. The slope of a line is change in y over change in x, \({\Delta y \over \Delta x}\), and the y-intercept is the y-coordinate where the line crosses the vertical y-axis.

To solve this equation, repeatedly do the same thing to both sides of the equation until the variable is isolated on one side of the > sign and the answer on the other.

-4z - 5 > \( \frac{z}{6} \)
6 x (-4z - 5) > z
(6 x -4z) + (6 x -5) > z
-24z - 30 > z
-24z - 30 - z > 0
-24z - z > 30
-25z > 30
z > \( \frac{30}{-25} \)
z > -1\(\frac{1}{5}\)

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.

(8a)(7ab) - (9a²)(9b)
(8 x 7)(a x a x b) - (9 x 9)(a² x b)
(56)(a¹⁺¹ x b) - (81)(a²b)
56a²b - 81a²b
-25a²b

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:

(y + 5)(y + 1)
(y x y) + (y x 1) + (5 x y) + (5 x 1)
y² + y + 5y + 5
y² + 6y + 5