The average of 2 masses means the total is 2 × 37.5 = 75 kg (worked out from the given 37.5). Mike = 1 unit, Calvin = 2 units.<br><br>[[model:questions/solutions/q4671.png]]<br><br>• Total mass → 2 × 37.5 = 75 kg<br>• Mike + Calvin = 3 units → 75 kg<br>• 1 unit → 75 ÷ 3 = 25 kg<br>• Calvin = 2 units → 2 × 25 = 50 kg<br><br>Calvin’s mass is 50 kg.<br>Check: (25 + 50) ÷ 2 = 37.5 kg. ✓