I typed in the following sentence in Grammarly and it keeps telling me that I had a problem with the subject-verb agreement:
How much of each tea makes up the mixed tea is not known. (My incorrect version according to Grammarly)
How much of each tea make up the mixed tea is not known. (Correct version according to Grammarly)
However, given that 'how much' refers to the amount of an uncountable noun, shouldn't the singular verb, makes, be more appropriate? 'of each tea' is a descriptive phrase so that it does nothing to do with the determination of verbs.