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 2 x 7) + (2 x 7 x 5) + (2 x 2 x 5)
sa = (28) + (70) + (20)
sa = 118

When solving an equation with two variables, 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.)

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.

4b - 6 = \( \frac{b}{-6} \)
-6 x (4b - 6) = b
(-6 x 4b) + (-6 x -6) = b
-24b + 36 = b
-24b + 36 - b = 0
-24b - b = -36
-25b = -36
b = \( \frac{-36}{-25} \)
b = 1\(\frac{11}{25}\)

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.

8a x 9b = (8 x 9) (a x b) = 72ab

The volume of a cylinder is πr²h:

v = πr²h
v = π(5² x 7)
v = 175π