Vat on goods sold in discount scheme

Dear Experts,

Please provide your view on below points W.r.t VAT Payment:

Example:

Cost of goods: 100

Normal Sale Price: 150

VAT @ 5% on above 150*5% = 7.5

Net Receivable from Customer= 157.5

Here we will pay Rs.7.5/- as VAT to the government

If THE SAME PRODUCT IS SOLD UNDER DISCOUNT SCHEME - - say 20% Discount

Cost of goods: 100

Normal Sale Price: 150

Discount @ 20% 150*20% = 30

VAT @ 5% on above (150 - 30) *5% = 6

Net Receivable from Customer= 126

Here we will pay Rs.6/- as  VAT to the government

My question is that the VAT should be paid on the Normal Sale Price of the product or Discounted Price of the product?

If we give some product as free of cost to some customer then we have to pay VAT on such product? If yes? Then on what amount (Cost or normal Sale price)?

Here we are not giving goods to customers as FREE SAMPLE or SALES PROMOTION or AS GIFT…

Thanks in advance...