Answer:
The length is 13
Explanation:
w+w+l+l= perimeter
if the length is 3m less than twice the width then let's do some math.
42 divided 2 =21. so the width and length of one side have to equal 21. For example, let's use 8 as the width. The length would be twice(16) minus three(13) 13 plus 8 is 21. WOW it equals half of it so no we know the length is 13 and the wdith is 8.