We have been given that Y and Z are points on the number line. The length of segment YZ is 9 units and Y lies at -12. We are asked to find the location of point Z.
Since Y and Z are located on number line, so Z can be either on left side of Y or on right side of Y.
When Z is on left side of Y, then we can set an equation as:
![Y-Z=9](https://img.qammunity.org/2021/formulas/mathematics/high-school/kniqk126zhaytkzgaenoljvh06ukjrt9hn.png)
![-12-Z=9](https://img.qammunity.org/2021/formulas/mathematics/high-school/1w0iowbd8zhngjhmwk85qqp8pcletjtoio.png)
![-12+12-Z=9+12](https://img.qammunity.org/2021/formulas/mathematics/high-school/m5o047q4oksext05whqpwn317lj7y6xkco.png)
![-Z=21](https://img.qammunity.org/2021/formulas/mathematics/high-school/x93bs5q5ht90ufw60rmipowjo17o3ppuu2.png)
![Z=-21](https://img.qammunity.org/2021/formulas/mathematics/high-school/ftf1xdx9sbj3yh7hwdljdqxnixcni898md.png)
Therefore, the location of Z will be
.
When Z is on right side of Y, then we can set an equation as:
![Z-Y=9](https://img.qammunity.org/2021/formulas/mathematics/high-school/mck3dk30j0sxxrxfg71s10nytf13yl5v90.png)
![Z-(-12)=9](https://img.qammunity.org/2021/formulas/mathematics/high-school/dad05kiyh9frausgyegg34vwb4oubd6988.png)
![Z+12=9](https://img.qammunity.org/2021/formulas/mathematics/high-school/hknplshgymq76741kngkjvx9cbof6b88bj.png)
![Z+12-12=9-12](https://img.qammunity.org/2021/formulas/mathematics/high-school/ztgnwi879pnsw6l0rjkczb3vj12zkb7ham.png)
![Z=-3](https://img.qammunity.org/2021/formulas/mathematics/high-school/d0cn8wznc9q1ivmr0azfa3f5q3cgbp9b9a.png)
Therefore, the location of Z will be
.