[
  "Draw a bar model: divide 280 into 7 equal parts. Jack gets 3 parts. Then split the remaining 4 parts in half for Jim.",
  "Jack: 3/7 x 280 = 120 cards. Remainder = 280 - 120 = 160 cards. Jim: 1/2 x 160 = 80 cards.",
  "Cards left = 160 - 80 = 80. Answer: 80."
]