[
  "Draw a bar model: Shortest = 3 units, Middle = 4 units, Longest = 5 units. Total units = 3 + 4 + 5 = 12.",
  "12 units = 60 cm, so 1 unit = 60 / 12 = 5 cm. Shortest = 3 x 5 = 15 cm, Longest = 5 x 5 = 25 cm.",
  "Difference: 25 - 15 = 10. Answer: 10 cm."
]