Proving an algebraic equality with fractions

[joex444]

How could I show that this is true:
$$\frac{m^2g^2-m^2}{ma+za}-\frac{zamg}{am+az+gm+gz}=-\frac{zma^2-z^2a^2}{ma-mg}$$

 

[Tide]

What have you tried?

 

[Doc Al]

Where does that expression come from? It doesn't look true to me. (Plug in a few values and see for yourself.)

 

[joex444]

yeah, it's not true...well, that makes it easy to show it's not true.