Solution :
Given :
Perimeter, P = 16 m
The length is 4 times less then three times the width.
Let the length be l and width be w.
Therefore, according to the equation :
Length, l = 3w - 4 ................(i)
Perimeter, P = 2(l+w)
16 = 2(l+w) ............(ii)
16 = 2l + 2w
8 = l + w ..............(iii)
Therefore solving equation (i) and (iii)
l = 3w - 4
8 = l + w
We get, w = 3 and l = 5