The short answer: it simplifies your problem. The equation
![169x+91=0](https://img.qammunity.org/2019/formulas/mathematics/middle-school/8kxixdrc4kifbzk08uvdi3i6c92c7r89of.png)
seems intimidating at first, but we can use that fact that 169 and 91 have the greatest common factor 13 (169 = 13 x 13 and 91 = 13 x 7) to rewrite this as
![image](https://img.qammunity.org/2019/formulas/mathematics/middle-school/revysehnzvrdexmtsqait1ql102d17jbi4.png)
and from there, it's much less of a headache to work out.