[
  "Express A in terms of B: A = 3/4 B.",
  "From B = 1/3 of (A+C), we get A + C = 3B. So C = 9/4 B.",
  "New B' = 1.5B. Ratio A:B':C = 3/4 : 1.5 : 9/4 = 3:6:9 = 1:2:3."
]