Quick brewing question

I had a recipe delivered to me with 3 kinds of hops. Northern Brewer, Colombus, and Cascade hops. It says to combine the northern brewer and colombus in a sack and boil for 5 minutes. and to dry hop with the cascade immediately after the finished wort is poured into the fermenter. Now in case you can't tell this is a Mr. Beer recipe. My question is, how long should i actually boil each hop type for, since i plan on doing a one hour boil of my wort.

You add the NB and Columbus into the kettle in the last 5 minutes of your 60 min boil. SInce your mr beer extract is pre-hopped, then there is no need for a bitterness addition, since that is what the hops in the extract do. The NB and the Columbus are really at this point for some fresh hop flavor and aroma. So you don't want to boil away the precious volitile oils. Then you add the cascade for the fresehest hop aroma since you are not boiling it.

Thanks Rev, starting the boil right now