A juvenile court may properly aggregate the commitment time triggered by a new offense, which is the subject of a new Welfare and Institutions Code section 602 petition and for which the authorized disposition is only a fine, with a previous offense which was the subject of a prior section 602 petition. Here, the minor’s new offense was possession of marijuana on school grounds, and the previous offense was for possession of a concealable weapon, for which the minor received probation. The trial court properly aggregated the three year maximum term from the first offense with the new offense to commit the minor to camp for the maximum term of three years. The prosecution was not obligated to file a supplemental petitioner under section 777 which would have required the juvenile court to make a finding that the previous dispositional order had been rehabilitatively ineffective.