Commentaire sur La Genèse 42:3

וירדו אחי יוסף AND JOSEPH S BRETHREN WENT DOWN — It does not call them “the sons of Jacob” (as in 5:5), thus suggesting that they regretted having sold him and that they had made up their mind to behave towards him in a brotherly manner and to redeem him at whatever price people might fix for them to pay (Midrash Tanchuma, Miketz 8).

וירדו אחי יוסף עשרה, the official selling grain in Egypt did not sell to more than one family per buyer. The reason for this restriction was intended to ensure that the buyers would not resell some or all of what they had bought, thus using what Joseph had stored as a source of enriching themselves.

אחי יוסף, Joseph's brothers. The reason they are described as Joseph's brothers instead of as Jacob's sons is that at that time they were determined to perform the brotherly act of redeeming him out of slavery.