Ok I am confused with these problems:

Solving for X and Y using substitution:

1. 2x+y=4

3x-y=6

2. 3x+15y=3

2x-5y=-28

3. 4x-5y=0

8x-10y+15

Solving for X and Y using linear addition:

4.5x-7y=2

3x=4y

5.10x+10y=40-5x

9x+2y=32-6y

6. 2x=8y+24

3x+5y=2