Answer:
[tex]\large\boxed{m=3}[/tex]
Step-by-step explanation:
[tex]\text{Let}\ k:y=m_1x+b_1\ \text{and}\ l:y=m_2x+b_2,\ \text{then}\\\\l\ \parallel\ k\iff m_1=m_2\\\\l\ \perp\ k\iff m_1m_2=-1\to m_2=-\dfrac{1}{m_1}\\--------------------------\\\\\text{We have the slope of the red line}\ m_1=3.\\\\\text{Then the slope of the green line}\ m_2=3[/tex]
