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 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.

3a⁶ - 8a⁶ = -5a⁶

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.

The sum of the interior angles of a triangle is 180°:
180° = a° + b° + c°
c° = 180° - a° - b°
c° = 180° - 43° - 70° = 67°

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

z² + 2z - 35 = 0
(z - 5)(z + 7) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (z - 5) or (z + 7) must equal zero:

If (z - 5) = 0, z must equal 5
If (z + 7) = 0, z must equal -7

So the solution is that z = 5 or -7