If you go to the “Calculations” part of the ribbon and from the “Field, Items and Set”, choose Calculated Field, then choose your fields in the new window
Busy at work so have not had much time to look at the pivot table, there is a lot going on in there .
If your wrap your code like this...=IFERROR(Resolved/(Pending+Resolved),0)...your work sheet will not drive you made with #DIV/0! and you will get the results you want.
Working with calculated fields in a pivot table in a pain in the neck and they can and do screw up your pivot so that all you are left with is a pile of crap, there are reams of internet data on how to use them but the reading of them would turn you to drink
To be honest if I had to use your data I would add the necessary sub and total fields in the raw data. I would also turn your raw data into a table so that any future fields or additional data would update in the pivot on refresh.
You could then construct a pivot table with the fields, subs and totals...this way you do not need calculated fields.It is far easier to add a column to the data field than to a pivot table. When I was trying to learn Access one of the first thing taught was to set out you needs on paper then construct and it is a sound piece of advice.