Brother = 1 unit, Sean = 4 units, so 5 units = $100 (given). Each $20, the $50 share and the $30 to give are worked out.<br><br>[[model:questions/solutions/q4151.png]]<br><br>• 5 units → $100<br>• 1 unit → $100 ÷ 5 = $20 (brother), Sean = $80<br>• Equal share → $100 ÷ 2 = $50 each<br>• Sean gives → $80 − $50 = $30<br><br>Sean must give his brother $30.<br>Check: Sean $80 − $30 = $50; brother $20 + $30 = $50. ✓