How to find y-intercept with 5x=1?
Well, you can't use the above to find a y-intercept.
The above is the equation of a straight line, 5x = 1, or x = 1/5.
In other wirds, the line x = 1/5 is a vertical line, cutting the x-axis at the point (x=1/5, y=0).
Since this is a vertical line, at x = 1/5, then it never cuts the y axis, There is no y-intercept.