How to remove duplicates in sqlite, but before that, what would be the check on other fields?

Question

SQLite

Good evening day. The program is written in C# + sqlite.
There is a table
Petrovich 10 30
Petrovich 20 10
It is necessary to remove duplicates in sqlite db, leaving one row in which the sum of the last two fields is the largest (that is, in this example, the first row). But if among these duplicates there is a row with the value of the sum, for example, more than 50, then remove absolutely all Petrovichs. I would like it to be quick sort, the table is extremely large.