Subject – nominative

Possessive – genitive

Direct Object – accusative

Indirect Object – dative

You also have ablative if this is for Latin.

I tell you the answer.

-Verb = tell (who does the telling? I do.)

-Indirect object pronoun = you (I’m telling you the answer; what am I doing? telling the answer. you just happen to be in the way. lol- it’s one way of putting it.)

A better way of seeing what’s happening would be to rearrange the sentence:

I tell the answer to you.

See?

He gives her the book.

Or: He gives the book to her.

Once again, the indirect pronoun would be “her”.

As to which verb should be used when, well that depends on the direct pronoun. Just see which makes more sense:

He give her the book. (He give…)

He gives her the book. (He gives…)

I tell you the answer. (I tell…)

I tells you the answer. (I tells…)

Hope this helps 🙂

as opposted to he and she if they were direct objects.