Learn Hardcore Ukrainian: Ми платимо або карткою, або готівкою; це зручно. - We pay either by card or in cash; it is convenient.

They are in the instrumental case (singular). Ukrainian often uses the instrumental to express the means or method of an action—here, the means of payment. Think of it as answering “with/by what?”: pay by card, pay with cash. That’s why the nouns end in -ою: картка → карткою, готівка → готівкою.

Can I say платимо картку or платимо готівку?

No. You don’t “pay a card/cash.” Use:

платити за + Accusative + чим?: Ми платимо за каву карткою. (We pay for the coffee by card.)
Or simply: Ми платимо карткою/готівкою. (We pay by card/cash.) If you want a direct object without за, use a different verb: оплатити/сплатити щось (e.g., оплатити рахунок).

Why is there a comma before the second або?

With the paired disjunctive conjunction або … або (either … or), Ukrainian normally puts a comma before the second part: або карткою, або готівкою. It separates the two alternatives clearly.

Could I write the sentence with just one або: Ми платимо карткою або готівкою?

Yes. One або is perfectly natural in neutral style, and then you don’t use a comma. Repeating або … або is a bit more emphatic/symmetrical and often used to stress a clear choice.

Why the semicolon before це зручно? Could I use something else?

The semicolon links two closely related independent clauses and keeps the first clause’s internal comma from causing confusion. You could also write:

Period: Ми платимо … готівкою. Це зручно. (most neutral)
Colon: Ми платимо … готівкою: це зручно. (the second explains the first)
Dash: Ми платимо … готівкою — це зручно. (adds an explanatory, informal feel)

What’s the difference between або and чи?

або usually presents a firm either/or choice, especially in statements: або карткою, або готівкою.
чи is very common in questions: Ви платите карткою чи готівкою? It can also appear in statements, sometimes sounding slightly less categorical than або.

Is the pronoun ми required? Could I say just Платимо …?

The verb ending already shows the person/number, so ми is optional if the subject is clear from context. Платимо або карткою, або готівкою; це зручно. is acceptable and natural in context.

What nuance does платимо have compared with заплатимо?

платимо is imperfective present: it can mean we are paying now or we (habitually) pay this way.
заплатимо is perfective future: we will pay (once, completed action). For a one-off future payment, say ми заплатимо карткою; for habits/policies, ми платимо карткою.

Is картою acceptable instead of карткою?

You will hear картою (from карта), but the recommended standard for a bank card is картка → карткою. Карта mainly means map (though some people use it for card colloquially). In careful speech/writing, prefer карткою or банківською карткою.

Why is it це зручно and not це зручне?

Ukrainian typically uses a predicative adverb to make general evaluations: це зручно (it is convenient). Use the adjective when it modifies a specific noun: Цей спосіб зручний.

Are there other natural ways to say this?

Yes:

Ми розраховуємося карткою або готівкою.
Оплата карткою або готівкою — це зручно.
To add what you’re paying for: Ми платимо за обід карткою.

Can I say за готівку instead of готівкою?

Both occur, but they’re used a bit differently:

Method with instrumental: платити готівкою (to pay in cash).
Commercial contexts often say: купити за готівку (to buy for cash). For paying itself, готівкою is the most straightforward.

What are the declension patterns behind -кою here?

Feminine nouns ending in -ка form the instrumental singular with -кою:

картка → карткою
готівка → готівкою This is the standard pattern for the “by means of” meaning used with many verbs (e.g., писати ручкою—to write with a pen).

Is ми платим okay, or does it have to be ми платимо?

Standard Ukrainian uses the full ending: ми платимо. Short forms like платим appear in casual speech in some regions, but they’re nonstandard in careful writing.