[
  "Convert both mixed numbers to improper fractions first, then subtract the numerators since the denominators are the same.",
  "4 2/7 = 30/7. 1 5/7 = 12/7. Subtract: 30/7 - 12/7 = 18/7 = 2 4/7.",
  "4 2/7 - 1 5/7 = 2 4/7. Answer: 2 4/7 (option B)."
]