Answer:
[tex]P=12m-8[/tex] units
Step-by-step explanation:
The perimeter of the rectangle with sides lengths of a units and b units is
[tex]P=2(a+b)\ units.[/tex]
In your case,
[tex]a=2m+3\ units\\ \\b=4m-7\ units,[/tex]
so the perimeter is
[tex]P=2(2m+3+4m-7)\\ \\P=2(6m-4)\\ \\P=12m-8\ units[/tex]