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
Graph shows x at 6 and y at -2