Answer:
[tex]L=15\ m[/tex]
Step-by-step explanation:
we know that
The perimeter of rectangle is equal to
[tex]P=2L+2W[/tex]
In this problem we have
[tex]P=42\ m[/tex]
[tex]W=6\ m[/tex]
substitute in the formula and solve for L
[tex]42=2L+2(6)[/tex]
simplify
[tex]21=L+(6)[/tex]
[tex]L=21-6=15\ m[/tex]
