How Subledger cost will be calculated?

Hello experts,

plz guide

How Subledger cost will be calculated?

I m using PWAC actual costing method-

For APRIL 13

                       Inventory valuation =  100 qty *  20 (item cost) = 2000

For May 13 

        Inventory valuation =  200 qty *  25 (item cost) = 5000

Please reply ,beacause i m confused about,

which method is right to calculate Subledger cost -

               1) Inventory movement (May 13 Inv valuation - Apr13 Inv valuation)

    =5000 - 2000

                 = 3000

or

               2) Transacted qty * item cost

    =100 * 25

    = 2500

Which is correct??

Plz guide

Regards,

Kunal