5) x-y=1

3x=3y=3

6) 2x-y=6
3y=-6x=18

Substitute x = y + 1

3(y +1) + 3y = 3

3y + 3 + 3y = 3
6y + 3 = 3
6y+3 -3 = 3-3

6y = 0
y = 0

x = y + 1
x = 0+ 1
x = 1
(1, 0)

6) substitute y = -2x +6
2x -1(-2x + 6) =6
2x + 2x - 6= 6

4x = 12

x = 3
y = 0
(3,0)