"I want to study with you."

Translation: Jeg vil studere med deg.

[Saengtawan2]

Jeg vil studere med dere

[Henry855458]

when do you use "å" for "to" and when do you not?

[Deliciae]

The infinitive marker, "å", is omitted after modal auxiliary verbs such as "vil/skal/må/kan/bør".

[Henry855458]

thanks

[Nelmo4]

When you use å and when you don't use it?

[Deliciae]

Please see my answer just above. :)