Hugh - who was additionally convicted of attempting to pervert the course of justice at police headquarters in Dundee the day after the serious sexual assault - denied inducing the girl away from her friends by offering her free cannabis.
At the High Court in Glasgow on Thursday, Cameron, 21, was handed an extended sentence of seven-and-a-half years, with five-and-a-half years in prison and two years on licence once released back into the community.
Judge Lord Lake said the girl was raped "multiple times", adding: "Your victim was young, very drunk and unable to look after herself.
Detective Constable Murray Scott said: "Hugh and Cameron Mullen will now face the consequences of their despicable actions.
The girl said she passed out in the moments before the attack and when she "came to", Hugh was raping her.
