simultaneous equations sub method?

Question 1
y = 2x - 1
4x + 2(2x - 1) = 5
4x + 4x - 2 = 5
8x = 7
x = 7/8

y = 7/4 - 1
y = 3/4

x = 7/8 , y = 3/4

Question 2
y = 2x - 8
3x + 2(2x - 8) = 2
3x + 4x - 16 = 2
7x = 18
x = 18/7

y = 36/7 - 8
y = 36/7 - 56/7
y = - 20/7

x = 18/7 , y = - 20/7

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

4x + 2y = 5
4x + 2(2x - 1) = 5
4x + 4x - 2 = 5
8x = 5 + 2
x = 7/8 (0.875)

2x - y = 1
2(7/8) - y = 1
y = 7/4 - 1
y = 3/4 (0.75)

∴ x = 7/8 (0.875) , y = 3/4 (0.75)

= = = = = = = =

2)
3x + 2y = 2
2y = 2 - 3x
y = (2 - 3x)/2

2x - y = 8
2x - (2 - 3x)/2 = 8
2[2x - (2 - 3x)/2] = 2(8)
4x - 2 + 3x = 16
4x + 3x = 16 + 2
7x = 18
x = 18/7

3x + 2y = 2
3(18/7) + 2y = 2
2y = 2 - 54/7
y = (-40/7)/2
y = -40/14
y = -20/7

∴ x = 18/7 , y = -20/7

-y=-2x+1
y=2x-1

2y=-4x+5
y=-2x+5/2

y=y
2x-1=-2x+5/2
4x=5/2+1
4x=7/2
x=7/8

replace in any of the primary equations now to get y
y=2x-1
y=2(7/8)-1
y=3/4


now the second pair.
2y=-3x+2, y= -3/2x+1
-y=-2x+8, y=2x-8

y=y
-3/2x+1=2x-8
-5/2x=-9
x=18/5

now replace in any of the equations,
y=2x-8
y=2(18/5)-8
y=-0.8