How can I say "to spend time with ?"
How can I say
- to spend hour(s) doing something;
i.e.
I spent 3 hours working on that paper.

- to spend time with someone,
i.e.
I like to spend time with my cats.

The examples are just there so you can get an idea of what I mean. I just would like to know how to express this idea of "spending time doing/spending time with".
Thank you in advance :)

Question

How can I say "to spend time with ?"
How can I say 
- to spend hour(s) doing something; 
i.e.
I spent 3 hours working on that paper.

- to spend time with someone,
 i.e.
I like to spend time with my cats.

The examples are just there so you can get an idea of what I mean. I just would like to know how to express this idea of "spending time doing/spending time with". 
Thank you in advance :)

Answer

I spent 3 hours working on that paper. 
If you are still working on it, I would say:その書類(しょるい)にとりかかって3時間がすぎました。
If you finished it after working on it for three hours, I would say: その書類を仕上げるのに3時間かかりました。
*There are other ways to say "working on that paper" dipending on the kind of "paper".

I like to spend time with my cats. 
私はねこといっしょに時間をすごすのが / すごすことが好きです。
However, I would say: 私はねこといっしょにすごす時間が好きです。

I hope this was helpful.