The discount received is a trade discount and not a cash discount. Trade discounts are deducted from the purchase price and not accounted for seperately. Since in the instant case the discount is given for both the basic price and VAT (which is recoverable), the entry would be as follows:
Purchases a/c Dr 90,000
(Rs 100000 less 10%)
Vat Recoverable a/c Dr 3,600
(Rs 4000 less 10%)
To Bank or Party's a/c 93,600
(depends if it cash or credit purchases)
(Also cash cannot be paid unless you want to attract the penal provisions of the Income Tax Act)
Therefore Inventory will be valued @ basic Purchases price i.e., Rs 90,000