Could you help me explain these following sentences
1. Over a billion dollars a year is spent on different kinds of cold medicine every year.
2. Millions of dollars are spent on Vitamin C every year.

I thought the subject in #1 sentence was in the plural somehow

Question

Could you help me explain these following sentences
1. Over a billion dollars a year is spent on different kinds of cold medicine every year.
2. Millions of dollars are spent on Vitamin C every year.

I thought the subject in #1 sentence was in the plural somehow

Answer

Sentence 1 is correct.

The subject, "Over a billion dollars', is a specific SUM OF MONEY. This is a singular concept, hence the singular verb.

Answer

Yes, you are correct, the subject of the first sentence ("dollars") is plural. So it should be "Over a billion dollars a year are spent..."