You can
put this solution on YOUR website!
y=3x+7
y=3x-9
y=3x+2
y=3x-2
y=3x+5
y=3x-8
All of those are parallel to y=3x+1,
or any other line of the form y=3x+b, and you can
pick any number for b. They all have the same slope.
And when lines slope the same way (have the same slope)
they are parallel.
Edwin