We can simplify each equation and find the solution.
6x + 2y = 15 can't be simplified further.
- 8x - 3y = 2 can't be simplified further.
4x - 4y = 6 on simplification gives 2x - 2y = 3 or x - y = 3/2
But, it does not coincide with the given equation.
- 3x + 3y = 6 on simplification gives x - y = - 2 coincides with the given equation.
Hence, - 3x + 3y = 6 can pair with x - y = -2 to create a consistent and dependent system.