A system of equations has infinitely many solutions. If 2y - 4x = 6 is one of the equations, which could be the other equation?

A. y = 2x + 6

B. y = 4x + 6

C. - y = - 2x - 3

D. - y = - 4x + 6

C. - y = - 2x - 3

The first step I suggest taking, is put 2y-4x = 6 into the same form as your answer choices:

2y - 4x = 6

2y = 4x + 6

y = 2x + 3

Now, we just look at our options choices and see which are the same. If we multiply both sides of y = 2x + 3 by - 1, then we get:

-y = - 2x - 3

This is the same as C. - y = - 2x - 3