Chapter 2 - Real Numbers - Chapters 1-2 Cumulative Review Problem Set - Page 92: 50

$P=6w$

Since the length is $2$ times the width, $w$, we must multiply $w$ by $2$ to find the length. This gives us a length of $2w$. The formula for the perimeter of a rectangle is $P=2l+2w$, where $l$ is the length and $w$ is the width. We plug in the values for width and length: $P=2(2w)+2(w)$ We multiply from left to right: $P=4w+2w$ We add to combine like terms: $P=6w$