Step 1: Theorem
Two lines are perpendicular if the product of their slope is equal to -1.
Two lines are parallel if their slope is equal.
Step 2:
[tex]\begin{gathered} \text{Write the general equation of a line in slope-intercept form} \\ y\text{ = mx + c} \\ \text{m = slope} \end{gathered}[/tex]Step 3:
Determine the slope from each equation
[tex]\begin{gathered} y\text{ = }\frac{7}{3}\text{ x + 6} \\ m_1\text{ = }\frac{7}{3} \\ y\text{ = }\frac{-3}{7}x\text{ + 4} \\ m_2\text{ = }\frac{-3}{7} \end{gathered}[/tex]Step 4: Determine if the two lines are parallel or perpendicular.
[tex]\begin{gathered} m_1\text{ }\ne m_2\text{ hence the lines are not parallel} \\ m_1\text{ }\times m_2\text{ = }\frac{7}{3}\text{ }\times\text{ }\frac{-3}{7}\text{ = }\frac{-27}{27}\text{ = -1} \end{gathered}[/tex]Final answer
Since the product of the two lines is equal to -1, hence, the two lines are perpendicular.
Perpendicular