I'm doing a study guide for Algebra 2. It is on Elimination and Subsitution
I need help on 2 of them

Subsitution:
2a = b + 4
2a = b - 6


Elimination:
8r - 4s = -1
3r + 7s = 6

Substitute the 2a to make life easy

b+4=b-6 ; You can do the rest

Elimination:
8r - 4s = -1
3r + 7s = 6

Is a bit harder:

Multiply top by -3 and bottom by 8 and add. Adding is easier than subtracting, so add. There will be less mistakes

8r - 4s = -1; multiply by -3, could also pick 7
3r + 7s = 6; multiply by 8 or could pick 4

You must use the -3,8 or the 7, 4 sequence

Add the equations.

r will drop out using -3,8 and s will drop out using 7,4

Substitute into one or the other eqn to get the other answer, or if it's not allowed (i.e. elimination only) the use the two pairs.
Ask teach what she wants when presented with problems such as this. Do it in front of the class.

I guess what I'm trying to say is that the method is really an elimination/substitution method, rather than elimination alone and I think that's how I learned it.