Merging 2 different pivot tables

[kkk]

I have 2 different pivot tables & want to merge them to get differences in
quantities of identical part numbers. For example :-

Table 1 - In Stock Table 2 - Required

Part Nr Qty Part Nr Qty
12 2 10 2
15 1 12 4
16 3 13 4
20 1 20 1
26 5 23 2
28 4
35 1

I want to get the difference between the two tables as if Table 1 were parts
in stock & Table 2 parts required and for the results only to show for the
parts in table 2

Output as below if possible

Part Nr Deficit
10 -2
12 -2
13 -4
20 0
23 -2

Is this possible?

Kenny