Translation:How much do olives and cookies cost?
How much do the olives and the cookies cost? is one of the accepted translations. You must have had an error somewhere in your answer. From now on, please either copy and paste or take a screenshot of your full, exact answer so we can help you see the real reason why it marked you wrong.
Thank you! I was totally confused, as I though it would be "quantorum" (plural genitive). Because olives AND cookies, or that "quanti" was the plural nominative, as it could be.
But "Quanti...constant" is indeed a fixed expression:
Between singular "Quanti constat" and plural "Quanti constant", only the verb does change.
So, it makes "quot" (how many) and "quantus" (how much, how big, what quantity) both invariable.
There's also a "quantus" declinated, but not when it's in this "how much does it cost" expression.
For instance, in "Quanta est audacitas tua? (How large is your audacity?), Quantus is declinated according to "audacitas".
Trying to make up for the mess I have generated, I went to check on my old high school Latin grammar book. Apparently, in Latin, with verbs like emo (I buy), vendo (I sell), veneo (I am bought), conduco (I rent sth to sb), loco (I rent sth from sb), redimo (I redeem), aestimo (I evaluate), sum/sto/consto (I cost - case at stake!) prices should be always expressed in ablative... except for the five adverbial genitives tanti, quanti, tantidem, pluris, minoris. In light of this, "quanti... constant" seems therefore correct. Sorry!
In older forms of English, you might have said, "How much cost olives?" Today, that is not standard English anywhere in the world (that I'm aware of), though it's common enough to hear from non-native English speakers. Especially in questions, you need to use the helper verb "do".
Many and much are synonyms.
They do have similar meaning, but as Rae.F has said, they're used differently. Since we're just talking about a price generically here without actually specifying countable items like "dollars" or "coins," the price is an abstract uncountable concept and we say "How much?"
english is not my native language
Unfortunately, you might not find much success on this course if you don't have a good command of English grammar. Duo is only a machine, and it isn't really set up to allow for grammatical mistakes very well.
They are equally valid. Neither is "more correct" than the other (and that's a strange concept). They just mean slightly different things.
How much do olives and cookies cost?
What's the price point in general? What price range should I expect to see when I look in this store or that store?
How much do the olives and the cookies cost?
These specific olives and these specific cookies--how much will I be paying for them when I get to the checkout line?