An equation is two expressions separated by an equal sign. The key to solving equations is to repeatedly do the same thing to both sides of the equation until the variable is isolated on one side of the equal sign and the answer on the other.

The area of a trapezoid is one-half the sum of the lengths of the parallel sides multiplied by the height:

a = ½(b + d)(h)
a = ½(6 + 2)(4)
a = ½(8)(4)
a = ½(32) = \( \frac{32}{2} \)
a = 16

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.

3a - 7 > \( \frac{a}{-1} \)
-1 x (3a - 7) > a
(-1 x 3a) + (-1 x -7) > a
-3a + 7 > a
-3a + 7 - a > 0
-3a - a > -7
-4a > -7
a > \( \frac{-7}{-4} \)
a > 1\(\frac{3}{4}\)

The circumference of a circle is the distance around its perimeter and equals π (approx. 3.14159) x diameter: c = π d. The area of a circle is π x (radius)² : a = π r².

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.

(7a)(4ab) + (4a²)(3b)
(7 x 4)(a x a x b) + (4 x 3)(a² x b)
(28)(a¹⁺¹ x b) + (12)(a²b)
28a²b + 12a²b
40a²b