Verb number when subject is percent [duplicate]

It is true that 'ten percent' is the subject here. Plural or singular - that must agree with the object ('pie') of the preposition 'of', following 'ten percent', to provide subject and verb agreement:

https://data.grammarbook.com/blog/singular-vs-plural/subject-and-verb-agreement-with-collective-nouns/

Example: Twelve percent of the building has/have been renovated. The subject is twelve percent, which will be either singular or plural depending on the object of the preposition that follows. In this sentence, the object of the preposition is building, which is always singular. So the correct answer is has.

'Pie' is singular, so is 'ten percent' in this particular sentence.