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 3 x 9) + (2 x 9 x 3) + (2 x 3 x 3)
sa = (54) + (54) + (18)
sa = 126

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, 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.)

2b(b - y)
2(-9)(-9 - 5)
2(-9)(-14)
(-18)(-14)
252

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.

6c - 5 = \( \frac{c}{4} \)
4 x (6c - 5) = c
(4 x 6c) + (4 x -5) = c
24c - 20 = c
24c - 20 - c = 0
24c - c = 20
23c = 20
c = \( \frac{20}{23} \)
c = \(\frac{20}{23}\)

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.

7a³ + 7a³ = 14a³