Answer:
Ms. Neville graded 80% of the papers and the student teacher graded 20% of them.
Step-by-step explanation:
Given a total of 75 papers, and Ms. Neville graded 60 of them, 15 remain for the student teacher. 75 - 60 = 15
Ms. Neville graded 60/75 = 0.8 = 80% of papers.
The student teacher graded 15/75 = 0.2 = 20% of papers.
Sanity check: 80% + 20% = 100%