A 16-year-old boy killed a young mother during an argument over drugs money, a court has heard.Paige Gibson, 23, was knifed in the chest outside her flat in Halifax, West Yorkshire, in the early hours of 7 June, Bradford Crown Court heard.A prosecutor told jurors the teenager was "increasingly angry" after she failed to give him money which he and his friends wanted for drugs.The 16-year-old, who cannot be named for legal reason, denies murder.