Sir let me tell that today was my ssc chsl exam and I am a beginner and I have only studied few chapters as I started preparing this month only and I was still able to do maths questions some through my academic knowledge and 5 questions were directly from these formulas , 2 or 3 questions could be done from the first formula only, there was one question from the work efficiency and. The profit loss formula as well ... So in short this lecture gave me atleast 8-10 marks .Thanks a lot