The table is one unit (= the chair) plus an extra 3 kg. Together they are 21 kg.<br><br>[[model:questions/solutions/q2550.png]]<br><br>• 2 units + 3 → 21 kg<br>• 2 units → 21 − 3 = 18 kg<br>• 1 unit (chair) → 18 ÷ 2 = 9 kg<br>• Table → 9 + 3 = 12 kg<br><br>The table is 12 kg.<br>Check: 12 + 9 = 21 kg, and 12 − 9 = 3 kg. ✓