How do I write one equations in slope-intercept form, and three other lines in slope-intercept form that are perpendicular to the first line ??

--
one line: y=mx+b

second line perpendicular
y= -x/m + c

of course, you have to know m, b, c.

-----
for the second line perpendicular, example if it
-2/3 slope. it will be use for the 3rd and 4th line perpendicular right ? and pick any value of for y-intercept for the 3rd and 4th ?