As you are aware, sentencing ranges in Washington are established by calculating the defendant's offender score or "points." While the calculation can be straightforward in some cases, there can be many variables (multipliers, washout periods, merger, juvenile convictions, comparability of out of state convictions, etc).
Based upon the limited information that you provided I am not certain that the defendant's socre is a five for a Burglary in the First Degree. It could be lower or it could be higher. Vehicle prowl is not a felony and would not score. A prior burglary conviction has a multiplier. An experienced criminal law attorney would need to sit down with the defendant's criminal history and spend some time working through it to determine the correct score.
If the defendant was in fact a five on a Burglary in the First Degree, his range would be 41 to 54 months in prison. That range does not include any enhancements that may have also been filed.
Please let me know if I can be of further assistance.