How does writing equivalent equations help you solve a system of equations?

Question

antonio_xx2 · Answer

Writing equivalant equations help you solve a system of equations because you have to add/subtract both equations, i.e.:
12x-15y=42
3x+15y=42

You can take out both of the 15 as they make a zero pair

anonymous · Answer

I'm sorry i'm still confused

anonymous · Answer

I'm a bit dyslecsic and i have trouble unferstandle things.

antonio_xx2 · Answer

You can write an equivalent equation from a selected equation in the system of equations to isolate a variable.  You can then take that variable and substitute it into the other equations.  Then you will have a system of equations with one less equation and one less variable and it will be simpler to solve.