Invoice raised in usd

Shubham Singhal (Student- ICAI) (175 Points)

13 September 2013  
A pvt. ltd. company is providing services to a mnc. the service is provided in delhi and invoice is raised to the co. in us dollars to us office. Now suppose a service is to be provided by pvt ltd co for 8lakhs incld service tax, on 1.4.2013 it raises performa invoice for 16000USD @ 50rs. in oct pvt ltd co gives invoice to mnc @ 60rs per usd and now in sep the payment is rcd by pvt ltd co for 65rs per usd. My ques is at what price the invoice has to be recorded in books and what will be the foreign exchange fluctuation profit.