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.

2a⁵ - 9a⁵ = -7a⁵

The perimeter of a triangle is the sum of the lengths of its sides:

p = x + y + z
p = 10cm + 11cm + 11cm = 32cm

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°).

To multiply monomials, multiply the coefficients (the numbers that come before the variables) of each term, add the exponents of like variables, and multiply the different variables together.

(3a)(3ab) - (8a²)(7b)
(3 x 3)(a x a x b) - (8 x 7)(a² x b)
(9)(a¹⁺¹ x b) - (56)(a²b)
9a²b - 56a²b
-47a²b

The area of a triangle is equal to ½ base x height:

a = ½bh
a = ½ x 1 x 6 = \( \frac{6}{2} \) = 3