To the pair be parallel, it must meet the (Mr = Ms) rule, Slope of the R line = Slope of the S line.
*The letters used to refer the lines could be any
I will designate the first line equation as "R" and the second "S".
![r: \: y = (3x / 7) + 11 \\ s: \: - 3x + 7y = 13](https://img.qammunity.org/2019/formulas/mathematics/high-school/su2phpzt4kr8ocqws5l8k6zf70bizlptgn.png)
Now we have to adjust the "S" line to the Slope-Intercept form:
![y = mx + n](https://img.qammunity.org/2019/formulas/mathematics/high-school/bu6bz55dmayiu9711saf7ciw98jgpubp0e.png)
![s: \: y = 3x + 13 / 7](https://img.qammunity.org/2019/formulas/mathematics/high-school/s9yhnekxoghoqehsmfuix7prqjyn35qobm.png)
To see better which is each term, i will make another little adjust:
![s: \: y = (3x / 7) + (13 / 7)](https://img.qammunity.org/2019/formulas/mathematics/high-school/drfigeuuhccdswhp5l8r0ndqus9ewa8xlz.png)
I will let the "R" line here too to view.
![r: \: y = (3x / 7) + 11](https://img.qammunity.org/2019/formulas/mathematics/high-school/pm1xh49xpfx7g37df967eh7i0m69lp373i.png)
Now we have to identify which terms are the Slopes (Mr, Ms) of the equations:
y = mx + n
-> s: y = 3x/7 + 11
-> Ms = 3/7 ; Ns = 11
-> r: y = 3x/7 + 13/7
-> Mr = 3/7 ; Nr = 13/7
Now see if they meet the condition (Mr = Ms):
3/7 = 3/7
Answer: The pair is parallel because the Slope of each line has the same value.