Answer:
![m\measuredangle8=110^o](https://img.qammunity.org/2023/formulas/mathematics/college/evfy8jawlj0r1rgg63ym9aboe2vn8thdbj.png)
Step-by-step explanation:
The angles 4 and 8 are equal; therefore,
![m\measuredangle8=m\measuredangle4](https://img.qammunity.org/2023/formulas/mathematics/college/vzc9bjg1ajn39tcrictoivrc51t9ql6rrk.png)
![3x+20=x+80](https://img.qammunity.org/2023/formulas/mathematics/college/zrx72j7nykummcbunvfs8wflf25d17d0dp.png)
Subtracting x from both sides gives
![2x+20=80](https://img.qammunity.org/2023/formulas/mathematics/college/hkqsuf9mqqf2po4hbl7rflcdln83j7h6nu.png)
Subtracting 20 from both sides gives
![2x=80-20](https://img.qammunity.org/2023/formulas/mathematics/college/kq6c8m2serj1diqvs8u070y96eo29kai6g.png)
![2x=60](https://img.qammunity.org/2023/formulas/mathematics/high-school/9ml0ie15wp2e6h55yvwr1c1zkxj5blozt3.png)
Finally, dividing both sides by 2 gives
![\boxed{x=30.}](https://img.qammunity.org/2023/formulas/mathematics/college/vkaeu0mtr0knbulz4wdrnyucvn6beolwzz.png)
With the value of x in hand, we now find the measure of angle 8.
![m\measuredangle8=x+80](https://img.qammunity.org/2023/formulas/mathematics/college/ef0d6iubeumldyflugsp832mh2ke4nea79.png)
![m\measuredangle8=30+80](https://img.qammunity.org/2023/formulas/mathematics/college/m4p8jgjx0zec7pz1sx5di6o9ie52umnnav.png)
![\boxed{m\measuredangle8=110^o\text{.}}](https://img.qammunity.org/2023/formulas/mathematics/college/lmgw0y98kom9ymznmfrnpvpkciaicomnzl.png)
Hence, the measure of angle 8 is 110.