Не могли бы Вы положить одну слойку и один бублик в пакет?

Не могли бы Вы... is a very common polite way to make a request in Russian.

Literally, it looks like Could you not..., which can seem negative to an English speaker. But in real usage, it means something like:

• Could you please...
• Would you mind...
• Could you...

So the не here does not make the request rude or actually negative. It softens the request and makes it more polite.

Compare:

• Положите... = Put... / Please put...
  Polite enough in many situations, but more direct.
• Не могли бы Вы положить... = Could you please put...
  More formal and softer.

Capitalized Вы is a polite written form when addressing one person respectfully.

Russian has:

• ты = informal you for friends, family, children
• Вы = formal or respectful you, and also plural you

In modern writing:

• Вы with a capital letter often shows extra politeness in letters, messages, signs, or formal service situations
• вы with a lowercase letter is also correct in many contexts, especially when referring to more than one person

So here, Вы shows respectful address to a customer or shop worker.

Russian often uses different verb forms depending on whether the action is seen as complete or ongoing/repeated.

• класть = imperfective
  Focus on the process, repetition, or general action
• положить = perfective
  Focus on one completed action

In a request like this, the speaker usually wants one complete action: put the items into the bag. That is why положить is natural here.

So:

• Не могли бы Вы положить... = Could you put...
  one completed action

Using класть here would sound less natural in this specific request.

This is because both nouns are in the accusative case, and the forms change differently depending on gender.

1. слойка is feminine

Its dictionary form is слойка.
Feminine nouns ending in -а usually change to -у in the accusative singular:

• одна слойка = nominative
• одну слойку = accusative

So both words change:

• одна → одну
• слойка → слойку

2. бублик is masculine inanimate

For most masculine inanimate nouns, the accusative singular is the same as the nominative singular:

• один бублик = nominative
• один бублик = accusative

So nothing changes here.

They are in the accusative because they are the direct objects of the verb положить.

The sentence is asking someone to put something. The things being put are:

• одну слойку
• один бублик

In Russian, direct objects often go into the accusative case.

So:

• положить что? = to put what?
• слойку
• бублик

That is why these nouns are in the accusative.

This is about motion versus location.

Russian often uses:

• в + accusative for movement into
• в + prepositional for being in

Here the idea is put into the bag, so Russian uses в пакет.

Compare:

• положить в пакет = put into the bag
• в пакете = in the bag as a location

Examples:

• Положите булочку в пакет. = Put the bun into the bag.
• Булочка в пакете. = The bun is in the bag.

Yes, very often.

You could say:

• Не могли бы Вы положить слойку и бублик в пакет?

This would still sound natural and correct.

Adding одну and один makes the request more specific: exactly one puff pastry and one bagel/ring-shaped bread.

In a shop, numbers are often included to make the quantity clear.

бы helps create a conditional or softened form, which is very common in polite requests.

Without getting too technical, могли бы is similar to English:

• could
• would be able to

So:

• Не могли бы Вы положить... = Could you please put...

The combination не могли бы is a standard polite request pattern in Russian.

Yes, Russian word order is fairly flexible.

The sentence:

• Не могли бы Вы положить одну слойку и один бублик в пакет?

is neutral and natural.

But Russian can move parts around for emphasis. For example:

• Не могли бы Вы в пакет положить одну слойку и один бублик?
• Одну слойку и один бублик не могли бы Вы положить в пакет?

These versions are still understandable, but the original sounds the most normal and neutral in a shop situation.

So English speakers should remember: Russian word order is flexible, but not random. Different orders can change emphasis or sound more marked.

Yes, положить is the infinitive.

That is because the structure Не могли бы Вы... is followed by an infinitive:

• Не могли бы Вы помочь? = Could you help?
• Не могли бы Вы подождать? = Could you wait?
• Не могли бы Вы положить...? = Could you put...?

If you used положите, that would be the imperative:

• Положите одну слойку и один бублик в пакет.

That is also correct, but it is more direct.
The version with Не могли бы Вы... is softer and more polite.

Пакет usually means a bag, especially a shop bag, plastic bag, or paper bag.

Сумка usually means a personal bag such as:

• handbag
• shoulder bag
• tote bag
• general carry bag

So in a bakery or shop, в пакет is exactly what you would expect if the seller is putting food into a store bag.

In a less formal situation, Russian would usually switch from Вы to ты, and the request might become less formal overall.

Possible versions:

• Не мог бы ты положить одну слойку и один бублик в пакет?
• Положи, пожалуйста, одну слойку и один бублик в пакет.

These are for someone you know well, or for an informal setting.

The original sentence with Вы is better for speaking to:

• a shop worker
• a customer
• someone you do not know well
• someone you want to address politely

A learner-friendly stress guide is:

Не моглИ бы Вы положИть однУ слОйку и одИн бУблик в пакЕт?

A few useful stress points:

• моглИ
• положИть
• однУ
• слОйку
• одИн
• бУблик
• пакЕт

This matters because Russian stress is mobile and not always predictable, so it is worth learning the stressed syllable together with each new word.