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 right angle measures 90 degrees and is the intersection of two perpendicular lines. In diagrams, a right angle is indicated by a small box completing a square with the perpendicular lines.

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

AD = AB + BD

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

b² - 5b - 14 = 0
(b + 2)(b - 7) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (b + 2) or (b - 7) must equal zero:

If (b + 2) = 0, b must equal -2
If (b - 7) = 0, b must equal 7

So the solution is that b = -2 or 7

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.