online sale

we sell product online , if any buyer buy that product which is of rs.5000/- we give him a coupon free worth rs 1000/- which can be cash against buying only books ( exempted in GST).
note : the books also given by us.

Now the query is whether
1. I hv raise bill 5000/- + GST
2. 5000+GST less discount 1000/-
3. 5000+GST one bill,
1000/- for books 2nd bill
& CNT for 1000/- against bill 5000+gst