[
  "Use 4980 and 5080 to find the step: 5080 − 4980 = 100.",
  "Work backwards from 4980: 4980 − 100 = 4880. That is 4780 + 100.",
  "After 5080: 5080 + 100 = 5180. Answers: 4880 and 5180."
]