Given, the perimeter of the rectangular billboard, P=42 m.
The length of the rectangular billboard is 9 m more than the width.
Let l be the length and w be the width of the rectangular billboard.
Then, the length can be expressed as,
[tex]l=9+w[/tex]The perimeter of a rectangle can be expressed as,
[tex]P=2(l+w)[/tex]Now, put l=9+w and P=42 m in the above equation to find w.
[tex]\begin{gathered} 42=2(9+w+w) \\ \frac{42}{2}=9+2w \\ 21=9+2w \\ 21-9=2w \\ 12=2w \\ \frac{12}{2}=w \\ 6m=w \end{gathered}[/tex]Hence, the length is,
[tex]\begin{gathered} l=9+w \\ l=9+6 \\ l=15\text{ m} \end{gathered}[/tex]Therefore, the length of the rectangular billboard is 15 m and the width of the rectangular billboard is 6 m.
