The area of a rectangle is equal to its length x width:

a = l x w
a = a x b
a = 7 x 8
a = 56

To factor a quadratic expression, apply the FOIL method (First, Outside, Inside, Last) in reverse. First, find the two Last terms that will multiply to produce 54 as well and sum (Inside, Outside) to equal -15. For this problem, those two numbers are -9 and -6. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² - 15y + 54
y² + (-9 - 6)y + (-9 x -6)
(y - 9)(y - 6)

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).

The coordinate grid is composed of a horizontal x-axis and a vertical y-axis. The center of the grid, where the x-axis and y-axis meet, is called the origin.

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.

7a⁹ - 8a⁹ = -1a⁹