What should I do to stop this

If one of my classmates , she was kinda like a friend cause she talks with me sometimes but I feel like she's just using me , I do my homework on time everytime but she would always come and pester me bout homework answer , I had to give her my answer everytime . I think of her as a friend and I don't wanna ruin our friendship cause she help me when I lost my text books and once when someone insulted me . I wanna continue to be a friend but I'm scared if I ask her to stop asking for homework answer.