## Precalculus (6th Edition) Blitzer

From equation (II), put the value of y in equation (I) \begin{align} & 9x-3\left( 3x-4 \right)=12 \\ & 9x-9x+12=12 \\ \end{align} $12=12$ (III) According to equation (III) $35=35$ indicates that the system has infinitely many solutions. Thus, the system has infinitely many solutions.