[
  "When subtracting decimals, align the decimal points. Subtract ones from ones, tenths from tenths.",
  "Ones: 7 - 1 = 6. Tenths: 9 - 5 = 4. Combine them: 6 ones + 4 tenths = ?",
  "7.9 - 1.5 = 6.4. Answer: 6.4."
]