Question 69899
Perimeter of rectangle=2*length+2*width=2L+2W=64 cm

Let x=width
Then 2x-4=length
 2L+2W=2x+2(2x-4)=64cm

2x+2(2x-4)=64 cm  get rid of parens

2x+4x-8=64 cm  add 8 to both sides

2x+4x-8+8=64+8 collect like terms
6x=72  divide both sides by 6
x=12 cm---------------width
2x-4=2*12-4=20 cm-------------length

CK

2L+2W=40+24=64cm 

Hope this helps----ptaylor