An equation is two expressions separated by an equal sign. The key to solving equations is to 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.

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°).

According to the Pythagorean theorem, the hypotenuse squared is equal to the sum of the two perpendicular sides squared:

c² = a² + b²
c² = 5² + 4²
c² = 25 + 16
c² = 41
c = \( \sqrt{41} \)

The volume of a cylinder is πr²h:

v = πr²h
v = π(7² x 3)
v = 147π

To solve this equation, isolate the variable for which you are solving (a) on one side of the equation and put everything else on the other side.

7a - 8x = 4a + x - 3
7a = 4a + x - 3 + 8x
7a - 4a = x - 3 + 8x
3a = 9x - 3
a = \( \frac{9x - 3}{3} \)
a = \( \frac{9x}{3} \) + \( \frac{-3}{3} \)
a = 3x - 1