Kumain kami ng biskwit bilang meryenda, at inilagay ko ang iba sa bag ko para mamaya.

Both are in the completed aspect.

In Filipino, it is often more accurate to talk about aspect rather than tense. These forms show that the actions are viewed as already done:

• kumain = ate / have eaten
• inilagay = put / placed

The sentence is describing completed actions: they ate some biscuits, and the speaker put the rest in the bag.

Because kami is exclusive we, while tayo is inclusive we.

• kami = we, but not including the person being spoken to
• tayo = we, including the person being spoken to

So Kumain kami means We ate, but the listener was not part of that group.

This is because the two clauses use different voice/focus patterns, which is a very important part of Filipino grammar.

• kumain kami ng biskwit uses an actor-focus verb
  
  • the actor is highlighted
  • kami is the main marked participant
• inilagay ko ang iba sa bag ko uses a patient-focus verb
  
  • the thing affected by the action is highlighted
  • ang iba is the main marked participant

So the sentence shifts focus:

• first clause: we did the eating
• second clause: the others / the rest are what got put into the bag

This is very normal in Filipino.

Because with this verb pattern, the doer is marked with genitive pronouns, not ang-form pronouns.

• ako = ang-form
• ko = genitive form, often used for the agent in many non-actor-focus constructions

So:

• inilagay ko ang iba = I put the others / the rest
• not inilagay ako ang iba

This matches the patient-focus verb inilagay.

Here, ng marks the non-topic object of the actor-focus verb kumain.

In kumain kami ng biskwit:

• kumain = ate
• kami = the actor/topic-like participant
• ng biskwit = what was eaten

So ng biskwit means some biscuits / biscuits as the thing eaten.

This is very common with actor-focus verbs:

• Bumili ako ng tinapay = I bought bread
• Uminom siya ng tubig = He/She drank water

It can be understood as singular or plural, depending on context.

Filipino nouns usually do not change form for plural the way English nouns do. So biskwit can mean:

• a biscuit
• biscuits

In this sentence, because of the context and because later it says ang iba meaning the others / the rest, it is natural to understand biskwit as biscuits.

If you want to make plurality explicit, you can use mga:

• mga biskwit = biscuits

Bilang here means as.

So bilang meryenda means:

• as a snack
• for a snack

It tells you the role or purpose of the biscuits.

• meryenda = snack, light meal between main meals
• bilang meryenda = as a snack

This use of bilang is common when something functions as something:

• bilang guro = as a teacher
• bilang regalo = as a gift

Ang iba means the others or the rest.

In this sentence, it refers to the remaining biscuits that were not eaten.

• iba by itself often means other / different
• ang iba can mean the others or the rest

So here:

• they ate some biscuits
• ang iba = the remaining ones
• the speaker put those into the bag

Yes, both are correct.

• sa bag ko = in my bag
• sa aking bag = in my bag

The version with ko after the noun is very common and natural in everyday speech.

Breakdown:

• sa = in / into / at / to, depending on context
• bag ko = my bag

Here sa bag ko means the biscuits were placed in the speaker’s bag.

It means for later.

• para = for
• mamaya = later / in a little while

So para mamaya expresses purpose connected to a later time:

• the speaker put the rest in the bag for later

It is a very natural way to say this in Filipino.

Yes, tsaka is possible in casual speech, but at is the standard written and.

• at = and
• tsaka = and, then, also; more conversational
• saka is also commonly seen

So:

• ..., at inilagay ko ang iba... sounds standard and neutral
• ..., tsaka inilagay ko ang iba... sounds more casual

Yes. In everyday speech, many speakers often say nilagay.

• inilagay = fuller form, often felt as more careful or formal
• nilagay = very common spoken form

Both are widely understood. In a learning context, it is good to recognize both.

It is somewhat flexible, but the original sentence is a very natural order.

Original:

• Kumain kami ng biskwit bilang meryenda, at inilagay ko ang iba sa bag ko para mamaya.

You can move some parts for emphasis, especially adverbial phrases, but not every rearrangement sounds equally natural.

For example, these are possible in certain contexts:

• Inilagay ko sa bag ko ang iba para mamaya.
• Para mamaya, inilagay ko ang iba sa bag ko.

But for a learner, the original order is a good default to follow.

A close structural breakdown is:

• Kumain = ate
• kami = we, not including you
• ng biskwit = biscuits / some biscuits
• bilang meryenda = as a snack
• at = and
• inilagay = put / placed
• ko = I
• ang iba = the others / the rest
• sa bag ko = in my bag
• para mamaya = for later

So very literally, it is something like:

Ate we some biscuits as a snack, and put I the rest in my bag for later.

That unnatural English order helps show how the Filipino pieces fit together.