Don gave 3/7 of his 280 cards to Jack, so 4/7 remains. He gave half of that remainder to Jim.<br><br>[[model:questions/solutions/q4337.png]]<br><br>• Jack → 3/7 × 280 = 120 cards<br>• Remainder → 280 − 120 = 160 cards<br>• Jim → 1/2 × 160 = 80 cards<br>• Left → 160 − 80 = 80 cards<br><br>Don had 80 cards left.<br>Check: Jack 120 + Jim 80 + Left 80 = 280. ✓