[tex]\begin{gathered} y=\frac{3}{7}x+11\text{ (1)} \\ -3x+7y=13\text{ (2)} \\ \text{Two lines are parallel when they have the samen slope. } \\ \text{Rewriting (2) as slope-intercept equation} \\ -3x+7y=13,\text{ solving y} \\ 7y=3x+13 \\ y=\frac{3x}{7}+\frac{13}{7} \\ They\text{ have the same slope and dif}ferent\text{ }y-intercept,\text{ hence} \\ those\text{ line are parallel} \end{gathered}[/tex]
