 Hello and welcome to the session. In this session we discussed the following question which says find x if 20, 10 and x are in proportion. If you are given any three numbers a, b and c and they are in proportion that is a is to b is proportional to b is to c then we have b square is equal to ac that is again product of extremes is equal to the product of the means and so we get b square is equal to ac. This is the key idea to be used in this question. Let's move on to the solution now. We are given that 20, 10 and x are in proportion which means 20 is to 10 is proportional to 10 is to x or you can say 20 is to 10 is equal to 10 is to x and so as they are in proportion so b square is equal to ac which means that 10 into 10 is equal to 20 into x. Product of extremes is equal to the product of the means which means 100 is equal to 20x to get the value of x we divide both sides by 20 and from here we have 20 cancels with 20, 0 cancels with 0 and 2 5 times is 10 therefore we get x is equal to 5. So x equal to 5 is our final answer this completes the session. Hope you have understood the solution of this question.