Below is an instruction that describes a task. Write a response that appropriately completes the request in Swahili. Please answer in Swahili.

### Instruction:
A rectangular plot of private property is fenced in by a chain-link fence. The long sides of the plot are three times the length of the short sides. One short side of the fence is rusted from being hit by a sprinkler and needs to be replaced. If all the sides of the fence together are 640 feet long, how many feet of fence need to be replaced?

### Response:
 Acha S iwe urefu wa upande mfupi wa uzio.
Hivyo, urefu wa upande mrefu wa uzio ni 3S.
Kuna 2 ya kila upande, hivyo uzio wote ni 2S + 2 * 3S = 2S + 6S = 8S.
Uzio wote ni 8S = futi 640.
Hivyo, upande mfupi wa uzio ambao unahitaji kubadilishwa ni S = 640 / 8 = <<640/8=80>>80 futi.