How many years of aggrevated robbery with deadly weapon serve?

My sister has been charged with aggrevated robbery with a deadly weapon and im sure she has another charge which is burgulary of habitation. But attorney says the aggrevated robbery w/ D W is the most important one that we should look at. Im in the state of Texas. And my sister is 18, this is her first time being arrested or charged with anything. How long do u think she will be in jail/prison for? do you think she's capable of probation?