Answer
perimeter = $2l+2w$
Work Step by Step
A rectangle is a 4-sided figure where opposite sides are equal in length.
The perimeter of a rectangle is the sum of the lengths of the sides.
If the length of a rectangle is l, there are 2 sides that have a length of l.
If the width of a rectangle is w, there are 2 sides that have a width of w.
The sum of the lengths of the 4 sides is then
$l+l+w+w$ or $2l+2w$.