The area of a triangle is equal to ½ base x height:

a = ½bh
a = ½ x 4 x 9 = \( \frac{36}{2} \) = 18

When solving an equation with two variables, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)

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 equal sign and the answer on the other.

-9z - 2 = \( \frac{z}{-9} \)
-9 x (-9z - 2) = z
(-9 x -9z) + (-9 x -2) = z
81z + 18 = z
81z + 18 - z = 0
81z - z = -18
80z = -18
z = \( \frac{-18}{80} \)
z = -\(\frac{9}{40}\)

A quadrilateral is a shape with four sides. The perimeter of a quadrilateral is the sum of the lengths of its four sides.

For parallel lines with a transversal, the following relationships apply:

• angles in the same position on different parallel lines equal each other (a° = w°, b° = x°, c° = z°, d° = y°)
• alternate interior angles are equal (a° = z°, b° = y°, c° = w°, d° = x°)
• all acute angles (a° = c° = w° = z°) and all obtuse angles (b° = d° = x° = y°) equal each other
• same-side interior angles are supplementary and add up to 180° (e.g. a° + d° = 180°, d° + c° = 180°)

Applying these relationships starting with z° = 22, the value of x° is 158.