Si on partage les frais, ce voyage est moins cher.

Si means if. It introduces a condition:

• Si on partage les frais = If we share the costs

In French, a si clause often states the condition first, followed by the result:

• Si on partage les frais, ce voyage est moins cher.

You could also reverse the order:

• Ce voyage est moins cher si on partage les frais.

Both are correct.

Grammatically, on can mean one/people/in general, but in everyday French it very often means we.

So here:

• Si on partage les frais really means If we share the costs

This is extremely common in spoken and informal written French. In more formal French, you might see:

• Si nous partageons les frais...

But on is much more natural in ordinary conversation.

Because the subject is on, and on takes third-person singular verb forms.

So:

• on partage not
• on partageons

Compare:

• je partage
• tu partages
• il/elle/on partage
• nous partageons

Even when on means we, the verb still stays singular.

Les frais means the costs, the expenses, or the shared expenses.

It is a very common expression in French. Even though English often says the cost in the singular, French often uses the plural les frais.

Common examples:

• partager les frais = to split the costs
• frais de voyage = travel expenses
• frais de livraison = delivery charges

So in this sentence, les frais refers to the money involved in the trip.

Partager les frais is the natural idiomatic way to say share/split the costs.

While diviser literally means to divide, it is not the usual expression here. A native speaker would normally say:

• partager les frais
• se partager les frais
• partager les dépenses

So this is mostly a vocabulary/collocation point: partager is the normal verb used with les frais.

Because voyage is a masculine singular noun.

French demonstrative adjectives agree with the noun:

• ce for masculine singular
• cette for feminine singular
• ces for plural

So:

• ce voyage = this trip
• cette voiture = this car
• ces voyages = these trips

French uses cher for expensive, and moins cher means less expensive or cheaper.

So:

• cher = expensive
• moins cher = less expensive / cheaper
• plus cher = more expensive

French does not use an equivalent of cheap in the same way English does here. The natural comparison is:

• ce voyage est moins cher = this trip is cheaper

Because French is phrasing the idea as this trip is cheaper, not it is cheaper.

The subject is explicitly:

• ce voyage = this trip

French often repeats the noun instead of using a pronoun if that makes the sentence clearer.

You could say:

• Il est moins cher if it is already very clear that il refers to le voyage.

But ce voyage est moins cher is more precise and natural in many contexts.

No. This sentence uses the present tense in both parts:

• Si on partage les frais → present
• ce voyage est moins cher → present

This is a very common pattern for real or likely situations:

• Si + present, present

It can express a general truth or an immediate practical result:

• If we share the costs, this trip is cheaper.

French also has other si patterns, such as:

• Si + present, future
• Si + imperfect, conditional

But this sentence uses the simple present-present structure.

Yes, absolutely.

• Si on partage les frais = natural, everyday French
• Si nous partageons les frais = also correct, a bit more formal or written

Both mean the same thing. In conversation, native speakers usually prefer on.

In this sentence, moins is usually pronounced roughly like mwan.

So:

• moins cher sounds roughly like mwan share (very approximate)

A few pronunciation notes:

• The s in moins is normally silent.
• ch in cher sounds like sh.
• The final r in cher is pronounced in standard French.

So the phrase flows as:

• moins cher → roughly mwan shair / mwan share

The comma is normal and helpful because the si clause comes first:

• Si on partage les frais, ce voyage est moins cher.

It separates the condition from the result.

If the main clause comes first, French often does not use a comma:

• Ce voyage est moins cher si on partage les frais.

So the punctuation here is standard.

Sometimes ce/cette can be translated as this or that depending on context, but the basic classroom translation is usually this.

So:

• ce voyage = this trip

If French wants to strongly distinguish this from that, it can use:

• ce voyage-ci = this trip
• ce voyage-là = that trip

Without -ci or -là, the exact English choice depends on context.