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.

7a + 8a = 15a

To multiply binomials, use the FOIL method. FOIL stands for First, Outside, Inside, Last and refers to the position of each term in the parentheses.

The first step to solve a quadratic expression that's not set to zero is to solve the equation so that it is set to zero:

b² - 6b + 3 = b - 3
b² - 6b + 3 + 3 = b
b² - 6b - b + 6 = 0
b² - 7b + 6 = 0

Next, factor the quadratic equation:

b² - 7b + 6 = 0
(b - 1)(b - 6) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (b - 1) or (b - 6) must equal zero:

If (b - 1) = 0, b must equal 1
If (b - 6) = 0, b must equal 6

So the solution is that b = 1 or 6

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

a = l x w
a = a x b
a = 3 x 8
a = 24

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 6 x 9) + (2 x 9 x 7) + (2 x 6 x 7)
sa = (108) + (126) + (84)
sa = 318