This is a system of equations, which means that we can solve it using either the elimination method or the substitution method. I will show elimination:
9x - 15y = 51
9x - 15y = -4
The top equation is found by multiplying the first equation by 3.
If you subtract the equations, you will find that it says 0 = 55. This is incorrect, so this system of equations has no solutions.