That's the instruction I have. Sorry for my bad English.

$\displaystyle mx - 4y = m$

$\displaystyle -4x + my = 2m + 4$

I Thought I should get both of the equations to y = ... , So:

$\displaystyle y = \dfrac{mx-m}{4}$

$\displaystyle y = 2 + \dfrac{4+4x}{m}$

And then:

$\displaystyle \dfrac{mx-m}{4} = 2 + \dfrac{4+4x}{m}$

$\displaystyle m(mx-m) = 8m +4(4+4x)$

$\displaystyle m^{2}x - m^{2} -8m-16-16x = 0$

And now I don't know how to continue...