Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_13 (students INTEGER, city VARCHAR, pupil_teacher_ratio VARCHAR)
### Question:
What is the highest number of students for schools in Campbell with pupil to teacher ratios over 25?
### Answer:
SELECT MAX(students) FROM table_name_13 WHERE city = "campbell" AND pupil_teacher_ratio > 25