 Welcome friends to this problem-solving session and we have learned in the previous session the property which is called anglesome property of a quadrilateral and we learned that the sum of all the four angles of a quadrilateral is 360 degrees, right? So now based on that, let us try to solve this problem. It says the angles of a quadrilateral are respectively 100 degrees, 98 degrees, 92 degrees. We have to find the fourth angle, right? So three angles are given, we have to find the fourth angle and we know the anglesome property. What is it? We know that. Let us now try to solve this question. So I will start with considering the fourth angle to be a variable, let's say x. So we are saying let the fourth angle be x, this is the starting point of my problem solution. Let the fourth angle be x. Then what? We can say the four angle added together, so 100 degrees plus 98 degrees plus 92 degrees plus x is equal to 360 degrees, isn't it? If you add 198 and 92, you will get 290 degrees, so 290 degrees plus x is equal to 360 degrees and now it is nothing but linear equation in one variable, so you can find out x is equal to 360 degrees minus 290 degrees which is equal to 70 degrees and my dear friends, this is the answer, 70 degrees, okay? So what's the learning in this kind of a question? It's a very simple question straight forward. Three angles are given, one, two and three, you have to find out the fourth one. I can find out the fourth one because I know the sum of the four angles of a quadrilateral, any quadrilateral like that is always 360 degrees, so if you take some, all the four angles put together is 360 degrees. So please keep this in mind, this property in mind and so that you don't invest so much of time in solving problems like this.