[
  "For equivalent three-term ratios, find the divisor that links one known pair of corresponding terms. Apply it to all others.",
  "The first term changed from 100 to 50: 100 / 2 = 50, so divide by 2. Second: 50 / 2 = 25. Third: 60 / 2 = 30.",
  "The missing terms are 25 and 30. So 100 : 50 : 60 = 50 : 25 : 30."
]