 Hello and welcome to this session. Let us discuss the following problem today. In an AP given A is equal to 5, D is equal to 3, An is equal to 50, find n in Sn. Now let us write the solution. It is given that A is equal to 5, D is equal to 3, An is equal to 50. Now we know that An is equal to A plus n minus 1, D. We will use this formula to find the value of n. Now substituting the values we get 50 is equal to 5 plus n is unknown, n minus 1 multiplied by 3, which implies 50 is equal to 5 plus 3n minus 3, which implies 3n is equal to 50 minus 5 plus 3, which implies 3n is equal to 45 plus 3, which implies 3n is equal to 48, which implies n is equal to 16. Now using this value of n we will find Sn, which is equal to n by 2 multiplied by A plus An, which is equal to 16 by 2, A is equal to 5 plus An is equal to 50, which is equal to this gets cancels by 8, so 8 multiplied by 55, which is equal to 440. Therefore n is equal to 16 and Sn is equal to 440 is our required answer. I hope you understood the question. Bye and have a nice day.