You give too little information to allow a detailed answer. A first degree without enhancements is between 10-20 years and since Robbery is a violent offense NERA is applicable, meaning 85% of the term must be served. The 2nd degree is NERA as well and the range is 5-10 years. There are numerous variables to consider to determine where in the range it falls or whether it can be reduced a level. The juvenile has a different range of disposition and may be facing a waiver hearing to adult Court. I cannot really say more without more information. Call if you like 908-687-6650
Mr. Cheser's answer is accurate on the sentencing ranges for the charged crimes. The likely outcome of the case depends on many facts including the state's evidence and the criminal histories of the accused. You also only mention two charges, but based on the inclusion of a handgun there are likely to be charges for the weapon, as well. Those charges also carry mandatory prison time if convicted. These are serious crimes that could result in years in prison. Both accused people need attorneys. Call me for a free consultation.
Anyone charged with these types of very serious crimes should contact an attorney with significant experience defending such cases. I would suggest that you contact a Certified Criminal Trial Attorney without delay.