For equations like

y= mx+ c

c is the y- intercept (value of y at x=0)

y= 3x+ 8 andy= 3x - 6

thus y interceept of our two lines are 8 and (-6)

So if we want a point on y axis equidistant from these lines

we need to have a value of y-intercept in between them

-- this means the value of y at x=0 of our answer should be in between 8 and (-6)

And the line should be parralel so that its equidistant throughout (see the attatchment)

thus answer is