[
  "85% of boys pass = 15% fail. 90% of girls pass = 10% fail. Boys failed = 3 * girls failed.",
  "So 0.15b = 3 * 0.10g = 0.30g, which gives b = 2g.",
  "Total failed = 0.15b + 0.10g = 0.15(2g) + 0.10g = 0.40g = 60, so g = 150, b = 300."
]