problem on VAT

Compute the VAT payable at each stage using ‘Invoice method from the particulars given below:
Particulars PROFIT (as % of Cost)
X sold the medicines
manufactured by it to
the distributors of
medicines-Y-at Rs. 4000 ------

II Y sold the medicines
to the Wholesalers-Z 56.25%

III Z sold the medicines
to the Retailers-A 25%

IV A sold the medicines
to the ultimate Consumers 25%

Assume that the VAT rate is 4% and that there was no value addition at various stages of sale except profit margin

you can also leave your ans at my id hereforeducation @ rediffmail.com