 Okay, and welcome to the session. I'm Hanika and I'm going to help you to solve the following question. The question says find n if n-1p3-Ap4 is equal to 1s29. Before solving this question, we should know that npR is equal to n factorial upon n-R factorial. This formula is the key idea in this question. I'll begin with the solution. We have to find value of n if n-1p3 is to np4 is equal to 1s29. Representing this ratio in terms of fraction we get n-1p3 upon np4 is equal to 1s29. We know that npR is equal to n factorial upon n-R factorial. Using this formula n-1p3 is equal to n-1 factorial upon n-1-3 factorial upon npR is equal to n factorial upon n-4 factorial and this is equal to 1 by 9. And this implies n-1 factorial upon n-4 factorial upon n factorial upon n-4 factorial is equal to 1 by 9. And this implies n-1 factorial upon n-4 factorial into n-4 factorial upon n factorial is equal to 1 by 9. We can cancel n-4 factorial from both numerator and denominator. So we are left with n-1 factorial upon n factorial is equal to 1 by 9. We know that n factorial is equal to n into n-1 factorial. So n-1 factorial upon n factorial implies n-1 factorial upon n into n-1 factorial is equal to 1 by 9. We can cancel n-1 factorial from both numerator and denominator. So we are left with 1 by n is equal to 1 by 9 and this implies n is equal to 9. Hence I require down-service 9. This completes the session. Hi and thank you.