[
  "Draw a bar model: the perimeter is 2 lengths + 2 breadths. Semi-perimeter = Length + Breadth.",
  "Semi-perimeter = 96 / 2 = 48 cm. Ratio L : B = 3 : 1, so total units = 4. 1 unit = 48 / 4 = 12 cm.",
  "Breadth = 12 cm, Length = 3 x 12 = 36 cm."
]