Brother = 1 unit, Terence = 3 units. Terence is 48 kg heavier, so the gap of 2 units is 48 kg.<br><br>[[model:questions/solutions/q2543.png]]<br><br>• Terence − Brother = 2 units → 48 kg<br>• 1 unit → 48 ÷ 2 = 24 kg (brother)<br>• Total = 4 units → 4 × 24 = 96 kg<br><br>The total mass is 96 kg.<br>Check: Terence 72 + brother 24 = 96 kg, and 72 − 24 = 48 kg. ✓