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).

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.

6z - 4 > 3 - 6z
6z > 3 - 6z + 4
6z + 6z > 3 + 4
12z > 7
z > \( \frac{7}{12} \)
z > \(\frac{7}{12}\)

A triangle is a three-sided polygon. It has three interior angles that add up to 180° (a + b + c = 180°). An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite (d = b + c). The perimeter of a triangle is equal to the sum of the lengths of its three sides, the height of a triangle is equal to the length from the base to the opposite vertex (angle) and the area equals one-half triangle base x height: a = ½ base x height.

Perimeter is equal to the sum of the four sides:

p = a + b + c + d
p = 5 + 6 + 3 + 7
p = 21

A rhombus is a parallelogram with four equal-length sides. A square is a rectangle with four equal-length sides.