Using only basic gates

Logisim Projects
1

Hi,
can I use components that I already built (by basic gates) in exercises that say using only basic gates?

2

also, in exercise 7, it says basic logic gates, does that include basic arithmethics?

3

If the question says only basic logic gates, then you must use only basic logic gates, nothing more.
If you would like to create sub-circuits using basic logic gates and use multiple instances of these sub-circuits, that is fine.

Basic logic include NOT, AND, OR, NAND, NOR, XOR, and NXOR only. Please see the footnote in instruction #14 b.