Pencil = 1 unit, pen = 4 units. The pencil is 48 g lighter, so the gap of 3 units is 48 g.<br><br>[[model:questions/solutions/q2523.png]]<br><br>• Pen − Pencil = 3 units → 48 g<br>• 1 unit (pencil) → 48 ÷ 3 = 16 g<br><br>The pencil is 16 g.<br>Check: pen 64 g − pencil 16 g = 48 g, and 64 = 4 × 16. ✓