같이 가자 can also be used to mean "wait for me!"

Stairway to Heaven made me never forget this line. Oppa was used SO MUCH in it!

[차은우]: ʻ같이 갈래?ʻ

I know, but someone studying Korean won't know what the difference between 오빠 and 형 is BECAUSE Duolingo doesnt have explanations