I do not have a copy of the plans to refer to, but the header size and the number of jack studs required to support the header vary, not only with the width of the opening, but also the width of the building, the height (number of floors), whether or not there is a center support beam or only side wall supports, and if the wall is a load bearing wall or a non load bearing wall as well as the local snow load.
Lots of variables.
The Table 502.5(1) [page 138 in the MN version of the IRC2006] is a guide to those sizes.