Answer:
Length= 8, Width= 4
Step-by-step explanation:
Say the length is l, and the width is w.
We can set l, the length as 2w, as it is double the length.
The perimeter= 2l + 2w= 24
Input l as 2w, get
4w+2w=24
6w=24, w=4.
Length is w*2, so length is 8.