What is the highest number of students for schools in Campbell with pupil to teacher ratios over 25?
CREATE TABLE "schools" (
  "school_name" text,
  "city" text,
  "students" real,
  "fte_teachers" real,
  "pupil_teacher_ratio" real
);
SELECT MAX("students") FROM "schools" WHERE "city"='campbell' AND "pupil_teacher_ratio">25;