[
  "Draw a bar model: At first, A:B = 7:10. Let A = 7u, B = 10u. After pouring 300 ml from A to B: A = 7u - 300, B = 10u + 300.",
  "New ratio (7u - 300) : (10u + 300) = 4 : 13. Cross-multiply: 13(7u - 300) = 4(10u + 300). 91u - 3900 = 40u + 1200. 51u = 5100, so u = 100.",
  "Total = 7u + 10u = 17u = 17 x 100 = 1700 ml. Answer: 1700."
]