Step-by-step explanation:
We know that:
- [tex]m\parallel n[/tex]
- [tex]m\angle2=60\°[/tex]
- [tex]m\angle1=m\angle3;m\angle2=m\angle4;m\angle5=m\angle7;m\angle6=m\angle8[/tex].; because they are opposite angles.
- Also, [tex]m\angle3=m\angle5[/tex]; because they are alternate interior angles.
- We can see that [tex]m\angle1+m\angle2=180[/tex]; because they are supplementary angles and they are on a straight angle.
So, based on those deductions:
[tex]m\angle1+m\angle2=180\\m\angle1+60=180\\m\angle1=180-60\\m\angle1=120[/tex]
Then,
[tex]m\angle1=m\angle3\\m\angle3=120=m\angle5=m\angle7[/tex]
All these angles are the same, because they are opposite (1 and 3), alternate interior (5 and 5), and opposite (5 and 7).
Therefore, [tex]m\angle7=120\°[/tex]