x-3y=-9
-x+3y=9
EQ1: x+9 = 3y
x/3 +3 = y
EQ2: 3y = x+9
y = x/3 + 3
Both equations are the same. It has an infinite number of solutions that satisfy y = x/3 + 3
x-4y=8
-x+4y=8
EQ 1: x-8 = 4y
x/4 - 2 = y
EQ 2: 4y = x+8
y = x/4 + 2
The slopes are the same, but the y intercepts are different. This system has no solutions.