Assuming your daughter is not sitting her GCSE or equivalent qualification early, it seems quite a bit of homework for a Y9 student - possibly the teacher is panicking about exams? Teachers do leave students to mark their own work or each others' without scrutiny on the basis that in Y9 in a subject with a clear answer it's pretty straightforward to mark, although presumably there is no credit for using the right method if the answer is wrong. Hopefully the teacher is going through any mistakes with the class so they understand how to do it correctly - I would check with your daughter for this, as if not, the teacher is not doing his/her job properly.
My DD's maths teacher is providing a Year 9 student with three X 1 hour exam papers to complete, mark and analyse this weekend. The teacher regularly sets huge amounts of work, all of which the students are expected to mark themselves using the marking scheme. My question is a) what is an acceptable amount of maths homework per week in Year 9 and b) is it acceptable to leave the students to mark their own work and not collect it in for scrutiny? Thoughts on this would be appreciated. TIA