Matrices and Determinants

Let $$\lambda, \mu \in \mathbf{R}$$. If the system of equations $$\begin{aligned} & 3 x+5 y+\lambda z=3 \\ & 7 x+11 y-9 z=2 \\ & 97 x+155 y-189 z=\mu \end{aligned}$$ has infinitely many solutions, then $$\mu+2 \lambda$$ is equal to :