[
  "Align the decimal points when subtracting decimals. Write 13 as 13.0 to match the decimal places.",
  "13.0 - 5.5 = 13.0 - 5.5. Subtract: 0 - 5 tenths needs regrouping. 13.0 = 12 ones 10 tenths. 10 tenths - 5 tenths = 5 tenths. 12 - 5 = 7.",
  "13 - 5.5 = 7.5. Answer: 7.5."
]