[
  "Draw a bar model: first find Length and Breadth from perimeter and ratio. Semi-perimeter = Length + Breadth.",
  "Semi-perimeter = 60 / 2 = 30 cm. Ratio L : B = 2 : 1, so total units = 3. 1 unit = 30 / 3 = 10 cm. Length = 20 cm, Breadth = 10 cm.",
  "Area = Length x Breadth = 20 x 10 = 200 square centimetres."
]