[
  "Let B = x. Then A = x + 2,000. Total: 2x + 2,000 = 10,000, so x = 4,000.",
  "A invested 4,000 + 2,000 = 6,000 dollars.",
  "Check interest: 8% of 6,000 = $480 + 10% of 4,000 = $400, total $880. Matches."
]