Answer:
[tex]4w+18[/tex]
Step-by-step explanation:
The formula for the perimeter of a rectangle is:
[tex]P=2(l+w)[/tex]
We know that the length l is w+9. Substitute:
[tex]P=2((w+9)+w)[/tex]
Combine like terms:
[tex]P=2(2w+9)[/tex]
Simplify:
[tex]=4w+18[/tex]
And that's our expression :)
And we're done!
