If we multiply both sides of the second equation by 5, then we go from y = 3x-8 to 5y = 15x-40. This is exactly identical to the first equation of the system.
Therefore, the two equations are equivalent just in slightly different forms. The two equations graph the same line which leads to infinitely many solutions.
The solutions are of the form (x, 3x-8) where x is any real number.
Since there are infinitely many solutions, we consider this system to be dependent.
