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 + 1 > \( \frac{a}{9} \)
9 x (-9a + 1) > a
(9 x -9a) + (9 x 1) > a
-81a + 9 > a
-81a + 9 - a > 0
-81a - a > -9
-82a > -9
a > \( \frac{-9}{-82} \)
a > \(\frac{9}{82}\)

An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite:

d° = b° + c°

To find angle c, remember that the sum of the interior angles of a triangle is 180°:

180° = a° + b° + c°
c° = 180° - a° - b°
c° = 180° - 70° - 66° = 44°

So, d° = 66° + 44° = 110°

A shortcut to get this answer is to remember that angles around a line add up to 180°:

a° + d° = 180°
d° = 180° - a°
d° = 180° - 70° = 110°

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.

A line segment is a portion of a line with a measurable length. The midpoint of a line segment is the point exactly halfway between the endpoints. The midpoint bisects (cuts in half) the line segment.

To factor a quadratic expression, apply the FOIL method (First, Outside, Inside, Last) in reverse. First, find the two Last terms that will multiply to produce 18 as well and sum (Inside, Outside) to equal 11. For this problem, those two numbers are 2 and 9. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² + 11y + 18
y² + (2 + 9)y + (2 x 9)
(y + 2)(y + 9)