https://preparationpoint.info/solved-past-papers-mcqs/ppsc-past-papers/ppsc-past-papers-2020/assistant-bs-16-land-record-authority-2020/four-years-ago-the-average-age-of-a-b-and-c-was-25-years-five-years-ago-the-average-of-b-and-c-was-20-years-as-present-is/