The entire length of this line is represented by AD which is AB + BD:

AD = AB + BD

Parallel lines are lines that share the same slope (steepness) and therefore never intersect. A transversal occurs when a set of parallel lines are crossed by another line. All of the angles formed by a transversal are called interior angles and angles in the same position on different parallel lines equal each other (a° = w°, b° = x°, c° = z°, d° = y°) and are called corresponding angles. Alternate interior angles are equal (a° = z°, b° = y°, c° = w°, d° = x°) and 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°).

The first step to solve a quadratic equation that's set to zero is to factor the quadratic equation:

c² - 2c - 15 = 0
(c + 3)(c - 5) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (c + 3) or (c - 5) must equal zero:

If (c + 3) = 0, c must equal -3
If (c - 5) = 0, c must equal 5

So the solution is that c = -3 or 5

Perimeter is equal to the sum of the four sides:

p = a + b + c + d
p = 6 + 8 + 3 + 6
p = 23

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.

9a - 4 > \( \frac{a}{7} \)
7 x (9a - 4) > a
(7 x 9a) + (7 x -4) > a
63a - 28 > a
63a - 28 - a > 0
63a - a > 28
62a > 28
a > \( \frac{28}{62} \)
a > \(\frac{14}{31}\)