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.

6a⁵ - 7a⁵ = -1a⁵

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 3) + (2 x 2 x 3)
sa = (28) + (42) + (12)
sa = 82

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.)

-2c(c - z)
-2(7)(7 - 3)
-2(7)(4)
(-14)(4)
-56

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)(4ab) + (5a²)(5b)
(8 x 4)(a x a x b) + (5 x 5)(a² x b)
(32)(a¹⁺¹ x b) + (25)(a²b)
32a²b + 25a²b
57a²b

Angles around a line add up to 180°. Angles around a point add up to 360°. When two lines intersect, adjacent angles are supplementary (they add up to 180°) and angles across from either other are vertical (they're equal).