A quadrilateral is a shape with four sides. The perimeter of a quadrilateral is the sum of the lengths of its four sides.

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.

4a - 6a = -2a

The surface area of a cube is (2 x length x width) + (2 x width x height) + (2 x length x height):

sa = 2lw + 2wh + 2lh
sa = (2 x 5 x 5) + (2 x 5 x 9) + (2 x 5 x 9)
sa = (50) + (90) + (90)
sa = 230

To solve this equation, isolate the variable for which you are solving (a) on one side of the equation and put everything else on the other side.

-5a - 8z = -8a - 8z + 5
-5a = -8a - 8z + 5 + 8z
-5a + 8a = -8z + 5 + 8z
3a = + 5
a = \( \frac{ + 5}{3} \)
a = \( \frac{}{3} \) + \( \frac{5}{3} \)
a = z + 1\(\frac{2}{3}\)

To solve this equation, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)

-7a(a - y)
-7(-1)(-1 + 6)
-7(-1)(5)
(7)(5)
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