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.

To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

9a⁸ + 9a⁸ = 18a⁸

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° - 68° - 47° = 65°

So, d° = 47° + 65° = 112°

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° - 68° = 112°

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).

The first step to solve a quadratic expression that's not set to zero is to solve the equation so that it is set to zero:

y² + 9y + 29 = -2y - 1
y² + 9y + 29 + 1 = -2y
y² + 9y + 2y + 30 = 0
y² + 11y + 30 = 0

Next, factor the quadratic equation:

y² + 11y + 30 = 0
(y + 5)(y + 6) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (y + 5) or (y + 6) must equal zero:

If (y + 5) = 0, y must equal -5
If (y + 6) = 0, y must equal -6

So the solution is that y = -5 or -6