Answer:
the highest single card player three could possibly have = {4}
Explanation:
total cards = 9
whole numbers on the cards = {1, 2, 3, 4, 5, 6, 7, 8, 9}
sum of player one's cards is 15, so the three cards owned by player one are:
player 1 = {3, 5, 7}
sum of player two's cards is 23, so the three cards owned by player two are:
player 2 = {6, 8, 9}
the three cards left for player 3 are:
player 3 = {1, 2, 4}
thus, the highest single card player three could possibly have = {4}