This paper considers a well-known linear system that is in widespread use. Any comparative statics exercise that is often employed in economics can be represented by a linear system. In order to guarantee that the solution to this linear system is nonnegative, previous research assumed that the coefficient matrix in this linear system was a Metzler matrix, i.e. each off-diagonal entry of this matrix was nonnegative. In this paper we relax this assumption, and apply this mathematical technique to study the profit-maximization pricing of a multi-product monopolist.