Wir widerrufen den Vertrag und frankieren das Paket.

Because the subject is wir (we). In the present tense, wir usually takes the same form as the infinitive for many verbs:

• wir widerrufen
• wir frankieren

So here the verbs are fully conjugated, even though they look like dictionary forms.

Both noun phrases are in the accusative case because they are the direct objects of the verbs, but their articles differ because the nouns have different grammatical genders:

• der Vertrag → den Vertrag
  masculine noun, so der changes to den in the accusative
• das Paket → das Paket
  neuter noun, so das stays das in the accusative

So the difference is caused by gender + case.

They are both in the accusative case.

Why? Because both verbs are transitive and take a direct object:

• widerrufen takes den Vertrag
• frankieren takes das Paket

A good basic question to ask in German is: What is being acted on?
Here, the contract is being revoked, and the package is being franked/postage-marked.

Because both verbs share the same subject: wir.

German, like English, often avoids repeating the subject when two actions are linked by und:

• Wir widerrufen den Vertrag und frankieren das Paket.

This is similar to English:

• We revoke the contract and frank the package.

You could repeat wir, but it would usually sound more repetitive:

• Wir widerrufen den Vertrag und wir frankieren das Paket.

In a normal German main clause, the conjugated verb comes in the second position.

In the first part:

• Wir = position 1
• widerrufen = position 2

Then the sentence continues with und plus another verb phrase that still belongs to the same subject:

• und frankieren das Paket

So this sentence is a good example of a very common pattern:

Subject + verb + object + und + verb + object

No. widerrufen is not separable.

That means it stays together:

• Wir widerrufen den Vertrag.

It does not split like a separable verb such as anrufen:

• Wir rufen ihn an.

This matters because learners often see prefixes and wonder whether they separate. In this case, widerrufen stays as one unit.

Not completely. It is irregular/strong in some forms, even though the wir form here looks regular.

For example:

• infinitive: widerrufen
• present: ich widerrufe
• past: ich widerrief
• past participle: widerrufen

So in this sentence, wir widerrufen is straightforward, but the verb does have irregular forms elsewhere.

By contrast, frankieren is a regular weak verb.

Not exactly.

Both can relate to ending some kind of agreement, but they are used differently:

• widerrufen = to revoke / withdraw / rescind
  often used in legal or formal contexts, especially when you cancel something by exercising a right of withdrawal
• kündigen = to terminate / cancel
  often used for contracts, subscriptions, apartments, jobs, etc.

So widerrufen sounds especially formal/legal here.

Because German usually uses the simple present tense where English might use either:

• we revoke
• we are revoking

So Wir widerrufen ... und frankieren ... can simply describe what is happening now, what usually happens, or what is being done in the current situation, depending on context.

German normally does not need a special progressive form here.

It is a real and correct word, but it sounds a bit specific and somewhat formal/technical, especially in postal contexts.

It means to put postage on something or frank it. In everyday speech, people might often use other expressions depending on the situation, but frankieren is perfectly standard, especially when talking precisely about postage.

So the sentence has a somewhat formal/business-like tone overall:

• widerrufen = formal/legal
• frankieren = specific/postal

German normally uses articles with countable singular nouns like these:

• den Vertrag
• das Paket

Leaving them out would usually sound wrong here.

The articles help show:

1. gender
2. case
3. whether the noun is definite or indefinite

So they are doing important grammatical work, not just adding extra information.