Answer:
[tex]\huge\boxed{width=12cm}[/tex]
Step-by-step explanation:
[tex]l-length\\w-width\\P-perimeter[/tex]
The formula of perimeter of the rectangle:
[tex]P=2l+2w=2(l+w)[/tex]
Substitute:
[tex]l=6w\\\\P=168cm[/tex]
[tex]168=2(6w+w)\\168=2(7w)\\168=14w\qquad|\text{divide both sides by 14}\\\\\dfrac{168}{14}=\dfrac{14w}{14}\\\\12=w\Rightarrow w=12(cm)[/tex]
