Gst on sale of goods on reduced prices and compensation of loss from supplier

Yes you have to pay gst on reduced sale price and ( compensation received (ie.including gst))

Yes you have to pay gst on reduced sale price and ( compensation received (ie.including gst))

As if the credit note has been issued where the goods found to be defective it must be included to determine value of supply. So ITC must reversed .

Note :
when Credit Note is issued as Secondary Discount as such Discount are given after the supply done. As in your case if your supplier re-value the the goods(chips) Rs40/- & pass on the credit note for Rs 60/- in that case in term of Section 15(3)(b) states that if Discount given after supply But it was not agreed upon before/at time of supply then Financial credit note can be issue. So that case no GST reversal needed.

In your case if supplier has issued the credit note by revrsing his Output Tax liability then you are surely required to reverse your ITC