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

A parallelogram is a quadrilateral with two sets of parallel sides. Opposite sides (a = c, b = d) and angles (red = red, blue = blue) are equal. The area of a parallelogram is base x height and the perimeter is the sum of the lengths of all sides (a + b + c + d).

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 equal sign and the answer on the other.

-3y - 2 = \( \frac{y}{9} \)
9 x (-3y - 2) = y
(9 x -3y) + (9 x -2) = y
-27y - 18 = y
-27y - 18 - y = 0
-27y - y = 18
-28y = 18
y = \( \frac{18}{-28} \)
y = -\(\frac{9}{14}\)

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.

5a + 6a = 11a

To multiply binomials, use the FOIL method. FOIL stands for First, Outside, Inside, Last and refers to the position of each term in the parentheses:

(y - 4)(y - 8)
(y x y) + (y x -8) + (-4 x y) + (-4 x -8)
y² - 8y - 4y + 32
y² - 12y + 32