To find the difference between these numbers you need to subtract 8.3 - 3.9
and that equals 4.4<span />
W - width
l - length
p - perimeter
The perimeter is 72 cm (p=72).
The length is twice the width (l=2w).
The formula for perimeter is 2w+2l=P.

Check the answer:

The length of the photo is 24 cm, the width of the photo is 12 cm.
I hope this helps. Have a good day.