Although the substitution method is hardest to figure out, once you know how to do it its as simple as 1,2,3!
To use the substitution method you must have a variable alone on one side. Sometimes the system comes with one equation like that and sometimes we have to do it our self. To get a equation to have a isolated variable all you have to do is put it into Y intercept form.
This method is so easy because you can use it on ANY system whereas other methods only work on some.
1. y= -3x+5 2. 2x-y=10
In this example all you have to do is plug the 1st equation in for y in the second equation