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.

2a + 2a = 4a

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.

-7y + 4 = -1 + 7y
-7y = -1 + 7y - 4
-7y - 7y = -1 - 4
-14y = -5
y = \( \frac{-5}{-14} \)
y = \(\frac{5}{14}\)

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 2b = (8 x 2) (a x b) = 16ab

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 8 x 6) + (2 x 6 x 3) + (2 x 8 x 3)
sa = (96) + (36) + (48)
sa = 180

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

a = l x w
a = a x b
a = 9 x 8
a = 72