Tom wants to run full-page ads in each of the magazines at some point during the four-week period.
However, he never wants to run full- and half-page ads in the same magazine in a given
week. Thus, the total number of full- and half-page magazine ads selected should not
exceed 12 (i.e., 4 weeks ? 3 magazines ? 1 ad per magazine per week = 12 ads).