[
  "Draw a bar model: Jill = 5 units, May = 1 unit, Sarah = 3 units. Total units = 5 + 1 + 3 = 9.",
  "9 units = 135 stamps, so 1 unit = 135 / 9 = 15. Jill = 5 x 15 = 75, Sarah = 3 x 15 = 45.",
  "Difference: 75 - 45 = 30. Jill received 30 more stamps than Sarah."
]