Step-by-step explanation:
The formula of a perimeter of a rectangle:
[tex]P=2l+2w[/tex]
We have P = 28. Substitute:
[tex]28=2l+2w[/tex]
Solve for w:
[tex]2l+2w=28[/tex] subtract 2l from both sides
[tex]2w=28-2l[/tex] divide both sides by 2
[tex]w=14-l[/tex]
Where [tex]0<l<14[/tex]
