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
AB = 1/2
BC = -2
CD = 1/2
DA = -2
Your percent is going to be <span>-203.008</span>
The answer is 492.126 :) Hope it helps!
So think about it this way, Which line is most associated with the dots?