How could you combine the following two sentence into a complex sentence with a dependent a dependent adjective the not wore a green coat. he carried his sister home

Your question does not seem finished. There is no such thing as a dependent adjective. Did you need a dependent adjective clause instead?

If that is the case, here is how to do this:

The boy who wore a green coat carried his sister home.

As you can see, the clause who wore a green coat is a dependent clause, adjective clause to be more precise, and thus the whole sentence is a complex sentence because it consists of an independent and a dependent clause.

The not wore a green coat as he carried his sister home.