[
  "When the tenths in the first number are too small to subtract, regroup 1 one as 10 tenths.",
  "1.4 = 14 tenths. 0.9 = 9 tenths. 14 tenths - 9 tenths = ? tenths.",
  "1.4 - 0.9 = 0.5. Answer: 0.5."
]