lets start by labeling the rectangle. let w = width so length(l) = w+4 (i.e 4 more than the width)
Perimeter of a rectangle= sum of all the sides= l+ w+l+w=2l +2w
now we know that p = 2l + 2w = 100
but we know that l=w+ 4
so
2(w+4) +2w=100
2w +8 +2w = 100
4w+8 =100
4w= 92
w=23
and if we substitute into 2l+2w= 100
we will get l =27.
