Question

Your friend often insist that you do your homework together but frequently copies your homework instead of contributing ideas.

Answer 1

Just tell your friend that you would like it if you both do equal amount of work
Maybe spilt it in half, you do the first half of the page and he does the second half of the page

Sure they'll understand

Answer 2

(Answering on my own thoughts)
A) I would tell my friend that I don't feel comfortable that he/she is copying my work. I would also tell her/him that they won't learn anything that way.
B) My friend might feel hurt at first because it'll seem to them that I don't want them to pass a subject. They will feel confused, too. But they'll realize later it was for their own good.
xx