35, 70, 105, 140, 175, 210, 245, 280, 315, 350, 385 so the answer is 11. I think this is correct.
However, it would probably be helpful for your daughter get additional help with her math homework from her teacher or a tutor. I would think it would be better for her to discuss with her teacher that she was unable to complete her homework because she is having difficulty with the concept rather than to turn in a perfect paper and have the teacher assume she understands the concepts/problems fully. Not a flame just an observation from a fellow parent.