Penawarannya sedemikian besarnya sehingga hasil bersih meningkat.

Penawarannya is penawaran + -nya.

The base word penawaran can mean offer, bid, proposal, or offering, depending on context.

The ending -nya here often makes the noun definite or refers back to something already known in the conversation. So it can mean things like:

• the offer
• his/her offer
• its offer

In many sentences like this, English will simply translate it as the offer if the owner is not important.

Indonesian usually does not need a word like is/was before an adjective.

So:

• Penawarannya besar = The offer is/was big
• Rumah itu mahal = That house is/was expensive

In this sentence, sedemikian besarnya functions as the predicate, so no separate word for was is needed.

Also, adalah would not normally be used here. Adalah is usually used before a noun phrase, not before an adjective like besar.

This is a formal pattern meaning so ... that ... or to such an extent that ....

So:

• sedemikian besarnya sehingga ... = so great that ...

The first part gives the degree, and the second part gives the result.

A simpler, more everyday version would be:

• begitu besar sehingga ...

So the structure is not random; it is a fixed way to express degree + result.

Here, besarnya is a more formal and emphatic form than plain besar.

The -nya in besarnya does not mean his/her/its here. Instead, it helps make the adjective feel more noun-like, something like:

• its greatness
• how great it was

So sedemikian besarnya is roughly like saying its size was so great that..., although in natural English we usually just say so great that....

A more ordinary version would be:

• Penawarannya sedemikian besar sehingga hasil bersih meningkat
• Penawarannya begitu besar sehingga hasil bersih meningkat

So yes, besar would also work in a more neutral style.

No. They look the same, but they do different jobs.

In penawarannya, -nya refers to the noun and often means something like the or his/her/its.

In besarnya, -nya is part of an emphatic/formal adjectival expression. It does not show possession there.

So:

• penawaran-nya = about reference/definiteness/possession
• besar-nya = about emphasis/style in this construction

This is a very common source of confusion for learners.

Sehingga introduces a result or consequence.

So here it means something like:

• so that
• with the result that
• to the point that

It is different from agar or supaya, which usually express purpose.

Compare:

• Ia belajar keras sehingga lulus.
  He studied hard, so he passed.

• Ia belajar keras agar lulus.
  He studied hard in order to pass.

In your sentence, sehingga shows the outcome of the offer being so large.

Literally, hasil bersih means clean result, but in real usage it usually means something like:

• net result
• net proceeds
• net profit
• net income

The exact English choice depends on the topic: business, finance, sales, accounting, and so on.

The word bersih often suggests that deductions, costs, or expenses have already been taken out.

Because meningkat is intransitive, while meningkatkan is transitive.

• meningkat = to increase / rise
• meningkatkan = to increase something

In this sentence:

• hasil bersih meningkat = net profit increased

Here, hasil bersih is the thing that goes up.

If you used meningkatkan, you would need an object:

• Penawaran itu meningkatkan hasil bersih = The offer increased net profit

So the sentence uses meningkat because hasil bersih is the subject of the result clause.

It is grammatical, but it sounds fairly formal and somewhat heavy or literary, especially because of sedemikian besarnya.

In everyday Indonesian, many speakers would say:

• Penawarannya begitu besar sehingga hasil bersih meningkat.
• Penawaran itu begitu besar sehingga hasil bersih meningkat.

Those versions feel more natural in conversation and ordinary writing.

So if you are learning for daily use, it is useful to understand sedemikian besarnya, but you will probably hear begitu besar more often.

Indonesian verbs do not usually change form for past, present, or future the way English verbs do.

So meningkat can mean:

• increases
• increased
• has increased

The time reference comes from context, not from the verb form itself.

For example:

• Kemarin hasil bersih meningkat. = Yesterday net profit increased.
• Sekarang hasil bersih meningkat. = Now net profit is increasing / increases.

The same is true for the first clause. Indonesian leaves tense more flexible unless a time word or context makes it clear.