2x-3y= 1.......(2)

(1) into (2):

2x-3(x-7)= 1

2x-3x+2 1= 1

-x=-20

x=20

Replace (1):

y=20-7= 13

(2) y=-x+2....( 1)

y=x- 1............(2)

( 1)-(2):

0=-x+2-x+ 1

2x=3

x=3/2

Replace (1):

y=-3/2+2= 1/2

(3) y-2x=-3...( 1)

2x+2y=8.......(2)

( 1)+(2):

y+2y=-3+8

3y=5

y=5/3

Substitution into (2):

2x+2(5/3)=8

2x=8- 10/3

x=7/3

(4) x-y- 1=0...( 1)

4(x-y)-y=5.....(2)

From ( 1): X-Y = 1

Substitution into (2):

4× 1-y=5

y=- 1

Replace (1):

x-(- 1)- 1=0

x=0

(5) 2y+x=5....( 1)

x-y=2.............(2)

( 1)-(2):

2y+y=3

y= 1

Replace (1):

2× 1+x=5

x=3

(6) 7y+4x= 19..( 1)

4x= 17+5y.......(2)

( 1)-(2):

7y= 19- 17-5y

12y=2

y= 1/6

Substitution into (2):

4x= 17+ 1/6×5

4x= 107/6

x= 107/24

(7) x+2y= 1 1....( 1)

3x-2y= 1 1.........(2)

( 1)+(2):

x+3x = 1 1+ 1 1

4x=22

x= 1 1/2

Replace (1):

1 1/2+2y = 1 1

1 1+4y=22

4y= 1 1

y= 1 1/4

(8) |x-2y- 1|+(2x-y-5)^2=0

x-2y- 1=0.......( 1)

2x-y-5=0.......(2)

( 1)-(2)×2:

x-2y- 1-(4x-2y- 10)= 0

-3x+9=0

x=3

Substitution into (2):

2×3-y-5=0

y= 1