There are many variables in this story that have yet to be mentioned. For example would the judge do work without collecting a fee? It says that the men extracted certain quantities of bread from their rucksacks, but the story never mentioned original ownership rights of the bread. It merely said that two of the individuals were carrying it. Are all five of the golden coins of equal weight and value? Are there relational aspects that we should consider? If we are to ignore all these, and merely go on the basis of contributor ownership then Jacob should receive 4 coins, and Joseph should receive 1 coin.

5 loaves need to be split into 3 pieces each
Therefore= 15 pieces

Jacob's contribution = 9 pieces
Jacob ate = 5 pieces
Jacob gave the group = 4 pieces

Joseph's contribution = 6 pieces
Joseph ate = 5 pieces
Joseph gave the group = 1 piece

Jacob contributed 4 times as much as Joseph, so to be fairly rewarded he should receive 4 times as much of the coins.