B is 1 unit. A is 5 units (5 times B). C is A − 400 = 5 units − 400. The three containers total 2900 ml.<br><br>[[model:questions/solutions/q8361.png]]<br><br>• 1 + 5 + 5 = 11 units, − 400 → 2900 ml<br>• 11 units → 2900 + 400 = 3300 ml<br>• 1 unit (B) → 3300 ÷ 11 = 300 ml<br><br>Container B has 300 ml.<br>Check: B 300 + A 1500 + C 1100 = 2900 ml. ✓