You can put this solution on YOUR website! divide by (a-3) both sides
y+1=x/(a-3)
subtract 1
y=(x/(a-3))-1. This is one answer
y=(x-a+3)/(a-3)); this is the same answer over a common denominator.
Can check. Let y=3 and a=5
x=8.
using the second answer above 3=6/2=3