Yes you are correct.........
Um.. Both of those equations are the exact same. Divide both sides of the first equation by 6. You get:

That is the exact same as the second equation. This system has an infinite number of solutions. 5x - 7y = -1 is a line, so basically every point on that line is a solution to the system.
For example,

and

would work, but so would

and
Every triangle’s inner angles’ addition equals to 180°
So if we find the x:
38°+x+2°+x=180°
40°+2x=180°
2x=180°-40°=140°
x=140°/2
x=70°
Now if we find the I hope this helped :)