Pre-Algebra Examples

 $\begin{array}{r} l = & 9 \\ w = & 8 - 12 w \end{array}$

Step 1

The perimeter of a rectangle is equal to the sum of all sides of the rectangle.

$l e n g t h + l e n g t h + w i d t h + w i d t h = 2 \cdot (l e n g t h) + 2 \cdot (w i d t h)$

Step 2

Substitute the values of the length $l = 9$ and width $w = 8 - 12$ into the formula for the perimeter of a rectangle.

$2 \cdot 9 + 2 \cdot (8 - 12)$

Step 3

Simplify each term.

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Step 3.1

Multiply $2$ by $9$ .

$18 + 2 \cdot (8 - 12)$

Step 3.2

Subtract $12$ from $8$ .

$18 + 2 \cdot - 4$

Step 3.3

Multiply $2$ by $- 4$ .

$18 - 8$

Step 4

Subtract $8$ from $18$ .

$10$ w