Explanation:
The length is 1m shorter than 4times the width which means
L=4w-1
perimetre= 38 is given
p=2(L)+2(W)
so we substitute 4w-1 that means
p=2(4w-1)+2(w)
38=8w-2+2w
38+2=8w+2w.....collecting like terms
40=10w........divide both side by 10
w=4