 Hello and welcome to the session. Let us understand the following question today. Find the sum of first 22 terms of an AP in which D is equal to 7 and 22nd term is 149. Now let us write the solution. Given to us that D is equal to 7, 22nd term is equal to 149 and we have to find the sum of first 22nd terms. So we know that An is equal to A plus n minus 1 D. An that is A 22 is given to us 149. So we substitute we get 149 is equal to A plus n is 22. So 22 minus 1 multiplied by 7. Which implies 149 is equal to A plus 21 into 7. Which implies 149 is equal to A plus 147. Which implies A is equal to 149 minus 147. Which implies A is equal to 2. Now we know that Sn is equal to n by 2 multiplied by 2A plus n minus 1 D. Now Sn that is S 22 that we have to find out. So S 22 is equal to n is equal to 22 by 2 multiplied by 2 multiplied by 2 plus 22 minus 1 multiplied by 7. Now here we see that this and this gets cancelled by 11. So it is equal to 11 multiplied by 4 plus 21 into 7. Which is equal to 11 multiplied by 4 plus 147. Which is equal to 11 multiplied by 151. Which is equal to 1661. Therefore sum of 22 terms is equal to 1661. Hence sum is equal to 1661. I hope you understood the question. Bye and have a nice day.