Use first operation Good Pcs and subtract Bad Pcs for each subsequent row to obtain subtotal

[deckhardt]

As you can see the good pcs sum up because good and bad pcs are keyed in at each operation.
Would like to have the subtotal for good pcs to be the first operation good pcs - sum of bad pcs by operation.

How can this be accomplished in a pivot table.

 

[iggydarsa]

Do you mean actual Good Pc in the first data is 16200 and Bad Pc is 197?
Even if so, how did you come up with 98%