here are some more examples of it's usage.
Q: 누구랑 같이 점심먹었어요?.(who have you had lunch with?)
1.남동생이랑 점심 먹었습니다.
2.남동생이랑 같이 점심 먹었습니다.
3.남동생하고 같이 점심 먹었습니다.
As you see, sometimes the word "같이" comes with "~이랑" and also "~하고" as in "~ 하고 같이" is the same meaning with "~이랑" in this sentence.
Both of them mean "with together" :)
in a nutshell, this word "이랑" can be used like this in sentences.
A 이랑 do something
A (이)랑 같이 do something
A 하고 do something
A 하고 같이 do something
in here,'A' could be a person or a pet.:)
Q: 누구랑 같이 산책했어요? (who did you go for a walk with?)
1.친구랑 같이 산책했어요
2.강아지랑 같이 산택했어요
(강아지: a puppy)
Q: 누구하고 같이 영화관 갔어요?(who did you go to the movie with?)
1.친구하고 같이 갔어요.
3.친구랑 같이 갔어요.