Question

the lenght of a rectangle is 4 cm less than three times the width. the perimeter is 64 cm

Answer 1

Let the width be x cm.
Then length=3x-4 cm.
Its perimeter is 64 cm.
We know that perimeter of a rectangle= 2(length+width)
So,
2(3x-4+x)=64
6x-8+2x=64
6x+2x=64+8
8x=72
x=9
Therefore,
length=(3×9-4)cm=(27-4)cm=23 cm.
Width=9 cm.

Answer 2

Let w be the width and l the length and 32 half of the perimeter
4-3w=32
-4        -4
--------------
-3w   =28
------   ------
  3         3

-1w     9 1/3
------    -------
  -1        -1
    w  = -9 1/3
The Width is -9 1/3