Given:
Angles A and B are vertical angles.
The measure of angle A is 8x + 1 and angle B is 21 – 2x.
To find:
The measure of each angle.
Solution:
We know that vertically opposite angles are always equal.
Angles A and B are vertical angles.
![m\angle A=m\angle B](https://img.qammunity.org/2022/formulas/mathematics/high-school/j19t8knoquxfz2f6qa4cmrbfo9ke8c00n3.png)
![8x+1=21-2x](https://img.qammunity.org/2022/formulas/mathematics/high-school/di4r7m3xh5jifv598z0r7vq3gpkqj9iuoq.png)
Isolate variable terms.
![8x+2x=21-1](https://img.qammunity.org/2022/formulas/mathematics/high-school/fyfmhwyujql4o5fhpkvkery9now8e9095n.png)
![10x=20](https://img.qammunity.org/2022/formulas/mathematics/high-school/13xzcx63lnfe1iw8kn6vyuisegms2znx6a.png)
Divide both sides by 10.
![x=(20)/(10)](https://img.qammunity.org/2022/formulas/mathematics/high-school/uny8rx9sbc3shaz4vbpzgr1mdwq20dkh5o.png)
![x=2](https://img.qammunity.org/2022/formulas/mathematics/high-school/44reazwucximx4d1uqoqmyb10x77od7ulw.png)
Now,
![m\angle A=8x+1](https://img.qammunity.org/2022/formulas/mathematics/high-school/nrsjayxtumqk5xx1grdgw4z39m9zh3z5sj.png)
![m\angle A=8(2)+1](https://img.qammunity.org/2022/formulas/mathematics/high-school/nk2x2rfke4p7h327mcvr6wl7w6ka27ji1y.png)
![m\angle A=16+1](https://img.qammunity.org/2022/formulas/mathematics/high-school/d77ezdhwdvxyq51ro6hq2bp12jrld5zt3r.png)
![m\angle A=17](https://img.qammunity.org/2022/formulas/mathematics/high-school/k7o8lhb86dra2aafudcaa71ve5wutsqi0o.png)
And,
![m\angle B=21-2x](https://img.qammunity.org/2022/formulas/mathematics/high-school/cqv76manmf8ylkzpxow95mm7x5vs324mk4.png)
![m\angle B=21-2(2)](https://img.qammunity.org/2022/formulas/mathematics/high-school/68xwxqza46ibdszqckdfaqhjh7ootxk1sq.png)
![m\angle B=21-4](https://img.qammunity.org/2022/formulas/mathematics/high-school/71u9pngou7ftd51ja7oitj6n4lxldpnqw7.png)
![m\angle B=17](https://img.qammunity.org/2022/formulas/mathematics/high-school/9dw0zpdec7n3vctyesbqeetnsrmwa6izo3.png)
Therefore, the measure of angle A and angle B is 17 degrees.