Pre-Algebra Examples

$- 12$ , $- 14$ , $- 16$ , $- 18$

Step 1

The mean of a set of numbers is the sum divided by the number of terms.

$\frac{- 12 - 14 - 16 - 18}{4}$

Step 2

Cancel the common factor of $- 12 - 14 - 16 - 18$ and $4$ .

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Step 2.1

Factor $2$ out of $- 12$ .

$\frac{2 (- 6) - 14 - 16 - 18}{4}$

Step 2.2

Factor $2$ out of $- 14$ .

$\frac{2 \cdot - 6 + 2 \cdot - 7 - 16 - 18}{4}$

Step 2.3

Factor $2$ out of $2 \cdot - 6 + 2 \cdot - 7$ .

$\frac{2 \cdot (- 6 - 7) - 16 - 18}{4}$

Step 2.4

Factor $2$ out of $- 16$ .

$\frac{2 \cdot (- 6 - 7) + 2 (- 8) - 18}{4}$

Step 2.5

Factor $2$ out of $2 \cdot (- 6 - 7) + 2 (- 8)$ .

$\frac{2 \cdot (- 6 - 7 - 8) - 18}{4}$

Step 2.6

Factor $2$ out of $- 18$ .

$\frac{2 \cdot (- 6 - 7 - 8) + 2 (- 9)}{4}$

Step 2.7

Factor $2$ out of $2 \cdot (- 6 - 7 - 8) + 2 (- 9)$ .

$\frac{2 \cdot (- 6 - 7 - 8 - 9)}{4}$

Step 2.8

Cancel the common factors.

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Step 2.8.1

Factor $2$ out of $4$ .

$\frac{2 \cdot (- 6 - 7 - 8 - 9)}{2 (2)}$

Step 2.8.2

Cancel the common factor.

$\frac{2 \cdot (- 6 - 7 - 8 - 9)}{2 \cdot 2}$

Step 2.8.3

Rewrite the expression.

$\frac{- 6 - 7 - 8 - 9}{2}$

Step 3

Simplify the numerator.

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Step 3.1

Subtract $7$ from $- 6$ .

$\frac{- 13 - 8 - 9}{2}$

Step 3.2

Subtract $8$ from $- 13$ .

$\frac{- 21 - 9}{2}$

Step 3.3

Subtract $9$ from $- 21$ .

$\frac{- 30}{2}$

Step 4

Divide $- 30$ by $2$ .

$- 15$