R. Kelly was sentenced on Thursday to 20 years in prison for child pornography and enticement of minors for sex but will serve all but one of those simultaneously with a separate 30-year sentence on racketeering and sex trafficking convictions.The sentence means Kelly could leave prison alive, when he’s about 80. Prosecutors had asked Judge Harry D. Leinenweber of the Northern District of Illinois to sentence the 56-year-old Grammy Award winner to 25 years and have him start serving them only after he completed his …