Good eye! It isn't a question of making sure the final letters are the same, but they do indicate how they should match. For example, la donna alta and l'uomo alto make it seem like the adjective must end with the same letter as the noun. But then you find adjectives that end in -e such as speciale or verde and you have to keep in mind that they only change if the noun is plural, gli uomini sono speciali or le torte sono verdi. There are other exceptions as well, such as adjectives that don't change at all.

Here are a few examples for the quanto case:

• Quanta frutta hai? How much fruit do you have?
• Quante donne mangiano frutta? How many women eat fruit?
• Quanti uomini bevono vino? How many men drink wine?
• Quanto sale abbiamo? How much salt do we have?

As you can see, most of them follow your rule, except for the last one. Sale is masculine singular, but might be misleading because it ends in -e. Nouns that end in -e can be either gender... it does take some memorization.

I hope that's somewhat clear!

Good question! I'd like to know the answer to your question as well, never heard of the "si mangia" construction before.

In terms of the second question, I think in this case the subject/verb order is different, because it's not a statement, so the question word goes before the verb and the subject gets bumped after the verb. Kind of like in German -- Wieviel Brot isst du? (really hoping there isn't a mistake in the German because lol it's been a while since I was actually practicing in a class)

How many breads? 1 bread. 4 breads. These could be correct when referring to types of bread, but it's asking for how much bread. (Lots, none, 4 loaves a week).

To me, much is singular, many is plural.

Yeah, I typed that as well as bread is both plural and singular in English. And when you ask how many, you use the plural.

"quanto pane mangi tu" it's about the order

I'd like to know as well...

Same here!

Ignoring the word order, mangi and tu are redundant. Tu is already implied by the conjugation of mangiare. It's wrong in this word order because that's the rule. Lei mangia / Tu mangi / Io mangio. Just like in English, if you say "Mangio Io", that means 'Eat I', not 'I eat'. So, Quanto pane mangi tu = How much bread do you eat you.

I wrote the same thing and got marked wrong because Duolingo said I should have used the voi form instead. I'm not sure why the tu form would be any less right than the voi form in this case.

Quanto mangi pane? = How much you eat bread. It's not the right translation for the exercise, although it is a workable sentence in Italian... if the noun at the end is actually a pronoun. Let's say you're doing a show with talking bread and you want to ask it about its eating habits: Quanto mangi, Pane? More realistically: Quanto mangi, Jenna? == Jenna, quanto mangi?

The subject always seems to go last, that's what the trend appears to be.

Reading the comments above, the last letter depends on gender of the noun.

Since 'pane' is male, you use 'quanto'.

You can usually simply use the same last letter as the noun, because that often indicates the gender of the npun. This does not work on nouns ending in e.

The gender of nouns ending in e varies. It's just something you either have to remember for each -e noun or just guess male or female (quanto or quanta) and hope! (Like i do!!)

Tu and Voi translate to "you (singular)" and "you (plural)" respectively

This article explains other uses for si: http://italianencounter.com/italian-grammar/italian-si/, but if you're only level 7, it doesn't really make sense that you're encountering that. That would translate roughly as "How much bread do people/you eat? Think of it in terms of a Google search question. It would be generic, like: "How much bread do you eat before you get sick from a gluten allergy?" You aren't really asking Google directly how much it can eat before it feels sick. You is generic, as in "How much bread does one need to eat?"

Anyway, if you got that answer from an alternative correct sentence, it's probably just there for advanced users who duolingo to keep the language fresh in their minds. It's not wrong, although the meaning is a little different.

In what way?

Reading some of the commemts above, 'si' is like a generic 'you', when not referring directly to the person you are speaking to.

Olde english 'si' would translate to 'one'.

Eg, How much sun do you need? (Not you personally). How much sun does one need? You would use 'si' here not 'tu'.

Quanto/Quanta - How much

Quanti/Quante - How many

Mangiano - they eat

As he said that's not true. The verb doesn't also mean the pronoun. The thing is, as there is a different form for each person (or almost) it's easier to just omit the pronoun, but you are never wrong if you put it in.

Not exactly. Remember when we learned the forms way back at the basics? Tu mangi; You eat. It's just the same, regardless of how redundant it is. ^^;

I don't know why DL wouldn't accept "Quanto pane mangi tu?" since that is correct. Italians habitually drop pronouns since the conjugation always identifies itself (i.e. first person singular ends with "o", second person singular ends with "i", first person plural ends with "iamo", etc). But there's no rule that demands the dropping of the pronoun. Actually using the correct pronoun with the verb might give you away as a nonnative speaker, but it isn't a punishable offence.