17When to use which method?
Elimination by equating coefficients
The elimination by equating coefficients is useful if both equations are already solved for the same variable or you can easily solve both equations for the same variable.
Substitution method
The substitution method is useful if one equation is already solved for one variable or can easily be solved for one variable. You can thus easily substitute it into the other equation.
Addition method
You should use the addition/subtraction method if both equations have the same variable with the same coefficient (e.g. in both equations). Based on the sign you decide whether you have to add or subtract.
