How to use SQL caculation combine two row data in one row ?

Hi, As below is My table, how to use additional calculate the two same row ID (PW.K3002.002) QTY data, but different location in one row ?
  e.g -PW.K3002.002(Facility) 399 + PW.K3002.002(MainRoller) 399 =  798
please advise, thank you


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