What color mixed with orange make green?

No "color" can be added to orange to make green. HOWEVER, you can try to revert orange back to yellow by adding yellow to it until it's as yellow as possible. You'll more than liking end up with a very light orange. Gradually add small amounts of blue until you've acquired the green you desire.

Side note: If you already have yellow in hand. There is no need for the orange. Just add blue to yellow!