Together with (と一緒に)
The phrase と一緒に (to issho ni) is used to convey the meaning of doing something together with someone or something.
Examples
友達と一緒に行きます。
I will go with my friend.
家族と一緒に旅行します。
I will travel with my family.
先生と一緒に勉強します。
I study together with my teacher.
Quick check
友達___一緒に行きます。