**Option 1**

Express one variable through the other:

2x+y=4;

x+6y=9;

3a+b=12;

c+8b=15.

Solve the system of equations by substitution:

{“(5y-x=6@3x-4y=4)┤

Solve the system of equations by substitution:

{(4x-3y=12@3x+4y=34)┤

Solve the system of equations by substitution:

{(6x+3=8x-3(2y-4)@2(2x-3y)-4x=2y-8)┤

* Solve the system of equations by substitution:

{((x+2y)/5+(3x-y)/3=5@2x-3y=-1)┤

**Option 2**

Express one variable through the other:

6x-y=18;

-a-5b=20;

18m-n=3;

-p-9q=4.

Solve the system of equations by substitution:

{(4y-x=11@6y-2x=13)┤

Solve the system of equations by substitution:

{(2x-3y=12@3x+2y=5)┤

Solve the system of equations by substitution:

{(4y+20=2(3x-4y)-4@16-(5x+2y)=3x-2y)┤

* Solve the system of equations by substitution:

{(7x-10y=5@(4x+1)/3-(5x-3y)/4=3)┤