Question 709483
Just treat i as any other number.  Finish by collecting and simplifying terms of y.



6 + (9x + y)i = 3x − 2i 
6+9xi+yi=3x-2i
6+9xi+yi-3x+2i=0
6+6xi+yi+2i=0
6+(6x+y+2)i=0
{{{highlight(6+(2+6x+y)i=0)}}}, This is IT, unless you really wanted y in terms of x, or x in terms of y.