https://preparationpoint.info/solved-past-papers-mcqs/ppsc-past-papers/ppsc-past-papers-2018/model-paper-91-assistant-in-agriculture-bs-16-2018-in-the-punjab-agriculture-department/if-the-total-strength-of-the-class-is-550-and-42-of-students-are-willing-to-attend-the-class-then-how-many-students-are-present/