1). 3x+y=5 (solid red) (2,-1)
x-2y=4 (purple)
2). 2y=3x+5 (1,4)
x=y-3
3). y=-1 (3,-1)
x=3
4). t+2s=-1 (t,s)=(-7,3)
s=t+10
5). 2b+a=11 (solid blue) (b,a)=(2,7)
a-b=5 (broken blue/red)
6). y=-1/4x+1 (4,0)
2y=x-4
7). y-x=5 (broken red/blue)
2x-2y=10 (broken red) Parallel: no solution
8). y=3-x
2x+2y=6 The equations are the same (x+y=3) so there are many solutions and no unique solution.