[
  "Use the perimeter formula: Perimeter = 2 x (Length + Breadth). Rearrange to find breadth.",
  "L + B = 9/10 / 2 = 9/20 m. L = 2/5 = 8/20 m. So B = 9/20 - 8/20 = 1/20 m.",
  "Breadth = 1/20 m. Answer: 1/20 m (option D)."
]