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.

7a - 7a = 0a

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.

-z + 2 > 4 + z
-z > 4 + z - 2
-z - z > 4 - 2
-2z > 2
z > \( \frac{2}{-2} \)
z > -1

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.

(6a)(2ab) + (9a²)(3b)
(6 x 2)(a x a x b) + (9 x 3)(a² x b)
(12)(a¹⁺¹ x b) + (27)(a²b)
12a²b + 27a²b
39a²b

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

a = ½bh
a = ½ x 9 x 4 = \( \frac{36}{2} \) = 18

A trapezoid is a quadrilateral with one set of parallel sides.